Northern Plains Region Licthic Materials

Materials Identification Guide

Northern Plains Region Lithic Material

Name	Natural	Non-heat treated points	Heat treated points	Color details	Primary found in:	Associated Formation / Member
Aarde Shale				Dull yellowish gray	Kansas	Aarden Shale Member of the Howard Limestone Formation
Absaroka Chert				Primarily green in color	Wyoming
Agate Jasper				Ranges from yellow to brown or green. Part if the material will be banded and be translucent while the remaining material will be mottled and opaque.	Western North America
Ahorn Quartzite				Primarily pink to maroon or a dark green to a greenish gray.	Montana	Hoadley Formation of the Belt Series
Alberta Ironstone AKA: Ironstone Concretions				Ranges from a dark rusty brown to black	Alberta
Alder Creek Jasper				Ranges from red to yellow	Idaho
Algal Chert Tiger Chert variation				Streaked ranging from most commonly a light gray to light brown, less commonly a very light gray to black or a very light brown to a very dark brown	Wyoming	Bridger Formation
Alibates Chert				Mottled color from most commonly reds, yellows, and oranges in iron rich areas to blues and dark greens	Texas, Oklahoma, New Mexico, Colorado, Kansas	Quartermaster Formation
Almond Orthoquartzite				Purple	Wyoming	Almond Formation of the Mesa Verde Group
Amazon (Colorado) Jade Amazonite / Feldsar				Ranges from a bluish green to green	Colorado
American Falls Obsidian AKA: Snake River Obsidian, Walcott Obsidian				Black, reddish brown streaking and patches may be present (mahogany obsidian).	Idaho	Picado and / or Twin Falls Volcanic Fields
American Nettie Quartzite Dakota Quartzite variant					Colorado	American Nettie Member of the Dakota Quartzite Formation
Amsden Chert				Ranges from most commonly gray or blue, but tan is also present.	Wyoming	Amsden Formation
Angel Agate				Pale greenish gray color with a chalky white cortex	Wyoming	Split Rock Formation
Antelope Chert Silicified Peat				Ranges in color from a purple to tans. White gastropod shells are found throughout the material.	Montana, North Dakota
Appekunney Argillite				Ranges from black to a gray or greenish gray with inclusions of white quartzite.	Montana, British Columbia	Appekunney Member of the Belt Series
Arbuckle Chert				Oolitic and ranges from a tan to a light gray color.	Oklahoma, Kansas	Arbuckle Formation, Osage Group
Argentine Chert				Ranges in color from a light tan to a pale to medium gray. Light mottling or streaking may be present.	Missouri, Kansas, Nebraska, Iowa	Argentine Member of the Wyandotte Limestone Formation
Arkansas River Agate					Colorado
Aspen Porcellanite				Ranges in color from white to pink.	Wyoming	Aspen Formation
Athabasca Quartzite				Ranges in color from a brown to a gray or silver gray color. Inclusions may be present.	Alberta, Saskatchewan	McMurray Formation
Austin Bluff Agate / Carnelian				Agate is mottled and ranges from rich red and brown color. Carnelian is a is cherry red	Colorado
Avon Chert AKA: Avon Valley Porcellanite				Porcelain white with brown chalcedony inclusions	Montana, Alberta, Saskatchewan
Ayers Quartzite					Montana, Alberta, Idaho, British Columbia
Badger Creek Chert					Colorado
Bacon Ridge Porcellanite				Pearly gray	Wyoming	Bacon Ridge Formation
Badlands Chert				Ranges from a yellowish brown to a pale reddish purple or dark yellowish orange	Wyoming, South Dakota
Badlands Moss Agate				Translucent medium yellowish brown to dark yellowish orange with dendritic inclusions.	Wyoming, South Dakota
Bald Mountain Dactite / Rhyolite					Colorado
Baldy Hill Jasper AKA: Cimarron River Jasper				Mottled color from most commonly varying shades of reds and yellows.	New Mexico, Colorado, Kansas, Oklahoma	Baldy Hill Formation
Banff Chert				Commonly banded ranging from a dark gray to a bluish black	Alberta	Banff Formation
Barger Gulch Chert				Similar to chalcedony with a translucent base with hues ranging from white to light yellow. Black dendritic, starburst inclusions are present. .	Colorado	Troublesome Formation
Basalt				Ranges from black to gray	Colorado, Wyoming, Montana, North Dakota, Alberta, Saskatchewan	Volcanic
Baxter Porcellanite				Ranges from a tan to a dark brown.	Wyoming	Baxter Formation
Bear Canyon Agate				Banded ranging from black and white to a dark gray and white.	Montana, Wyoming
Bear Den Kaolin					North Dakota	Bear Den Member of the Golden Valley Formation
Bear Gulch Obsidian AKA: See page for list of names				Black	Idaho
Beaver River Silicified Sandstone AKA: Beaver Creek Quartzite, Muskeg Valley Microquartz				Slightly mottled ranging in color from brown to orange and light to medium gray	Alberta, Saskatchewan
Belt Argillite				Ranges from a medium gray to a greenish gray with casts commonly present.	Montana, Idaho	Belt Supergroup
Belvoir Ranch Chert				Ranges in color a dark brown to a purplish or reddish brown color. Purplish veins and white circular inclusions are present.	Wyoming
Bethany Falls Chert				Ranges from light to dark gray	Minnesota, Iowa, South Dakota, Nebraska	Swope Formation
Beulah Chert				Mottled with colors of red, gray, buff, and purple	Colorado	Beulah Formation
Big Horn Chert AKA for Phosphoria Chert				Ranges from colors of red, maroon, purple, orangish red, green, black and white.	Wyoming, Montana	Phosphoria Formation
Big Horn Plume Agate				Clear white or light blue matrix with black or metallic plumes	Wyoming
Big Sandy Petrified Wood AKA: Petrified Palm Wood				Ranges from tans to dark browns. Wood grain and white inclusions are present. The cortex is commonly white.	Wyoming	Green River Formation
Big Southern Butte Obsidian AKA: Webb Springs Obsidian				Black	Idaho
Bingham Quartzite				Most commonly white and banding may be present	Utah	Bingham Quartzite Formation
Bijou Hills Quartzite AKA: Ogallala Orthoquartzite				Range from a dull gray white to a drab olive greenish color. It typically has various minerals that can give a salt and pepper appearance	South Dakota, Nebraska	Ogallala Formation
Black and White Agate				Banded black and white	South Dakota	Chadron Formation
Black Buttes Jasp-Agate				Ranges from a reddish brown to a dark gray with white quartz veins, quartz filled vugs and inclusions of yellow to orange, dark brown, purple.	Wyoming
Black Forest Silicified Wood AKA: Bijou Basin and Elizabeth Petrified Wood				Layered and banded with colors of tan, beige, brownish gray, and brown or a butterscotch colored jasper with large dark brown mottling and visible wood grain.	Colorado	Dawson Formation
Black Hills Petrified Wood AKA: Edgemont Petrified Wood					South Dakota	Dakota Formation
Black Hills Quartzite				Ranges from a tan to brown or purple to maroon or gray.	Wyoming, Montana	Fall River Formation
Black Quartzite				Ranges from a dark charcoal gray to black.	Alberta
Blairmore Chert					Alberta
Blanco Basin Mudstone				Primarily a reddish brown, but may range to red, maroon, purple green or gray, mottling may be present	Colorado, New Mexico	Blanco Basin Formation
Blue Forest Petrified Wood				Opalitic blue with grain and rings present.	Wyoming	Laney Member of the Green River Formation
Blue River Agate					Nebraska, Kansas	Eskridge Formation
Blue Springs Chert					Nebraska, Kansas
Blue Valley Agate				White to light blue or pinkish matrix with pink bands or patches	Kansas	Wreford Formation
Bonner Quartzite				Ranges from most commonly pinkish gray to pale red. Less commonly reddish gray to red or greenish gray.	Montana	Bonner Quartzite member of the McNamara Formation, Missoula Group
Boone Chert AKA: Sallisaw Chert, Grand Falls Chert, Ti Valley Chert				Ranges from a light gray to white	Oklahoma, Arkansas, Missouri, Kansas	Boone Limestone Formation
Boulder Jasper				Mottled with colors ranging from a yellowish brown to red. Intricate patterned swirls and speckles of translucent silica are present.	Utah
Bowman Chert AKA: Bowman Porcellanite				Porcelain white with brown chalcedony inclusions	Montana, Alberta
Browns Park Chert				Similar to chalcedony with a opaque base of white and translucent hues ranging from light yellow, light to dark gray or light brown.	Colorado, Wyoming	Browns Park Formation
Brushy Basin Chert				Banded, white in color with pastel shades of tan, pink, green, and orange with banded or swirls of darker shades of brown, reddish brown, or gray.	Colorado, Utah, Arizona, New Mexico	Brushy Basin Formation
Brushy Basin Quartzite					Colorado, Utah, Arizona, New Mexico	Brushy Basin Formation
Bubble Gum Agate / Chalcedony				Mottled or banded and ranges from shades of tans, reds, and white	South Dakota
Buffalo Peaks Chert				Ranges in color from from yellowish tan color with linear black to gray inclusions	Colorado	Troublesome Formation
Burro Canyon Chert				Variegated ranging from white to yellow, tan to medium brown, light to medium gray, light to medium green or shades of red	Colorado, Utah	Upper Burro Canyon Formation
Burro Canyon Quartzite				Ranges from off white to tan light gray or light green. May have mottling of darker gray.	Colorado	Upper Burro Canyon Formation
Caineville Agate / Jasper / Petrified Wood				Colors of white, gray, green, purple, orange, and red. The jasper is red and the petrified wood is shades of brown and tan	Utah
Cannonball Mountain Obsidian				Black	Idaho
Cashman Quarry Dactite				Commonly a light grayish white, but may range to a dark gray	Montana
Castle Rock Petrified Wood					Colorado
Cat Head Chert				Ranges from a pale yellowish gray to a slightly mottled yellowish gray, black when heat treated	Manitoba	Cat Head Member of the Red River Formation.
Catlinite AKA: Red Pipestone				Ranges from a brownish red to a deep red color	North Dakota, South Dakota, Iowa, Minnesota	Sioux Quartzite Formation
Cedar Mountain Agate / Jasp-Agate				Multi-colored agate / moss / flame / plume agate with dendritic inclusion and jasp-agate is red and yellow with white and blue streaks.	Wyoming	Bishop Conglomerate Formation
Chadron Chert				Mottled and ranges from tan or yellowish brown to red or gray. Vugs filled with chalcedony or drusy quartz may be present.	Wyoming, South Dakota, Nebraska	Chadron Formation
Chalky Butte Chert					North Dakota	Chalky Butte Member of the Chadron Formation
Challis Chancedony				Ranges from gray to a bluish gray or white.	Idaho
Charlie Creek Chert				Ranges from red to gray and white with black dendritic inclusions are present.	North Dakota
Charma Jasper				Mottled mustard yellow with intrusions of white quartz.	Colorado, New Mexico
Cherry Creek Petrified Wood AKA: Running Creek Petrified Wood				Shades of reds, browns, and whites	Colorado
Cherokee Chert					Kansas
Chesterfield Obsidian AKA: Smith Creek Obsidian				Black	Idaho
Cheyenne Quartzite					Kansas	Cheyenne Sandstone Formation
Circle Cliffs Petrified Wood				Colors of browns, grays and black with veins and patches of white. Wood grain and rings are present.	Utah
Cisco Agate AKA: Blood Spot Agate, Pigeons Blood Agate				Ranges from bright red to pink, pinkish tan, and salmon color.	Utah
Cisco Jasper / Petrified Wood				Petrified Wood has colors of yellow, pink, red and bluish gray chalcedony.	Utah
Cisco Pink Chalcedony				Light pink color	Utah
Clarke Lake Jasper				High quality red jasper	British Columbia
Cloverly Quartzite				Ranges from a light gray to gray and a grayish red to a purple.	Wyoming	Cloverly Formation
Coal Creek Metaquartzite				Ranges from white to light gray or pink	Colorado	Coal Creek Formation
Conant Creek Obsidian AKA: Buggy Springs Obsidian				Black	Idaho
Cottonwood Chert AKA: Manhattan Chert				Grayish brown with patches of shades of white.	Nebraska, Kansas	Cottonwood Limestone Formation
Cougar Creek Obsidian				Black with many white "snowflake" inclusions	Wyoming
Crazy Horse Petrified Wood				Ranges in color from black to tan or blue with a wood grain appearance The cortex is white.	Wyoming
Crazy Woman Creek Petrified Wood				Colors of white, tan, brown, and black, a wood grain appearance is present.	Wyoming
Crescent Hill Chert				Primarily homogenous and ranges in color from purple to red or orange, black and green. Inclusions are commonly present.	Wyoming, Montana	Crescent Hills Basalt Formation, Absaroka Supervolcanic Group
Creston Quartzite				Ranges from a pale green to a bluish grey or maroon	British Columbia, Montana, Idaho	Creston Formation
Cripple Creek Jasper				Shades of predominately browns with whites and light greenish gray commonly forming hills and valleys with a greenish gray sky	Idaho
Cripple Creek Turquoise AKA: Hidden Treasure Turquoise					Colorado
Cumberland Flats Petrified Wood					Wyoming
Cumbres Pass Chert				Ranges in color from an opaque mottled white gray to tan. Chalcedony inclusions are throughout the chert matrix.	Colorado
Curio Hill Agate				Banded agate	Colorado
Curzon Chert				Mottled and primary medium to light gray, but may range to a light yellow brown to a light olive brown or brownish gray.	Nebraska, Iowa, Missouri	Curzon Limestone of the Topeka formation
Cypress Hills Quartzite				Light grayish color.	Alberta	Cypress Hills Formation
Dakota Quartzite AKA: Dakota Orthoquartzite				Ranges in color from reds to browns	Colorado, South Dakota, Nebraska, Kansas	Dakota Formation
Dawson Petrified Wood AKA: Elizabethan, Parker, Cherry Creek Petrified Wood				Ranges from a yellowish tan with clear or white linear inclusions to a reddish tan with dark tan inclusions	Colorado, Nebraska	Dawson Formation
Day Creek Chert				Ranges from a mottled very light pale blue to a grayish blue or a reddish blue. Tan and brown mottling or streaking may be present	Kansas, Oklahoma	Day Creek dolomite of the Cloud Chief formation
Deadman Chert				Ranges from gray to a greenish gray	Idaho	Deadman Limestone Formation
Deadwood Quartzite				Type 1 course grain quartzite ranging from dark red to orange Type 2 fine grain quartzite ranging from a yellowish gray to brown	South Dakota, Wyoming	Deadwood Formation
Dean Lake Chert				Ranges from a blackish gray to a tannish gray or bluish gray / black.	Montana	Dean Lake Member of the Madison Limestone Formation
Deep Lake Metaquartzite				Ranges from a grayish white to a dark gray or brownish gray.	Wyoming	Early Algonkian
Delaney Rim Agate				Mottled ranging from white, black, and tan to brownish black and brown.	Wyoming
Del Norte Plume Agate AKA: Embargo Plume Agate				Banded clear matrix with golden or orangish yellow plumes.	Colorado
Deuel County Petrified Wood					Nebraska	Oligocene Chadron Formation
Doggett Chert				Variegated or breccia ranging most commonly a light tan or buff to brown. Less commonly white to light blue or gray, dendritic inclusions are present	Montana, Alberta	Pilgrim Limestone Formation
Dollar Mountain Chert / Chalcedony				Mottled ranging from caramel / yellow / brown to red / pink / maroon or light and dark gray.	Wyoming	Bighorn Formation
Douglas Mountain Jasper AKA: Cross County Jasper, Tank Peak Jasper					Colorado	Morgan Formation
Dry Creek Quartzite					Montana, Alberta
Dry Head Agate AKA: Big Horn Agate				Banded and ranges in color from red, pink, yellow, orange, white and brown with swirls and "eyes" present.	Montana, Wyoming	Phosphoria Formation
Dry Lakes Agate					Wyoming	Split Rock Formation
DuBois Moss Agate				Ranges from green to gray with brown or black dendritic inclusions.	Wyoming
Duck Rock Jasper				Banded with colors of yellow, red, and brown cemented with silica.	Utah
Eastern Petrified Wood AKA: Lake Butte Petrified Wood				Ranges from reds to yellows with inclusions of milky white. wood grain" and rings are present in the material.	Montana (Eastern region of Yellowstone)	Langford Formation
Eden Valley Petrified Wood				Various colors of agate often including full limbs, knots, cracks, braches, burrows and grain. The outer coating if coated with algae.	Wyoming	Green River Formation
Elimia Agate AKA: Turritella Agate				Black to brownish gray or brownish black matrix with light gray snail shells.	Colorado, Wyoming, Utah	Green River Formation
Elk Creek Basalt				Ranges from a dark gray to black	Wyoming, Montana, Idaho	Elk Creek Basalt Member, Washburn Group, Absaroka Supervolcanic
Emmons Peak Quartzite AKA: Uinta Quartzite				Ranges from an off white to a red or reddish purple.	Utah, Colorado, Wyoming	Emmons Formation
Empire Gulch Rhyolite				White with many small clear sharp quartz crystals	Colorado
Ervine Creek Chert				Ranges from a light medium gray to a dark gray. Larger white specks are formed by fossils	Nebraska, Iowa, Kansas, Missouri	Ervine Creek Limestone Member, Deer Creek Limestone Formation
Etherington Chert				Mottled with colors of primarily gray with shades of brown, red, and purple. Quartz inclusions and micro fossils are present.	Alberta, British Columbia	Etherington Formation
Everson Creek Chert					Montana, Alberta	South Fold - Thrust Belt
Eyebrow Chert				Ranges in color from tan to orange, red or brown. Less commonly white to clear or dark brown to black may be present. Dendritic inclusions are present.	Montana	Madison Formation
Fantasque Chert				Bluish gray	Yukon, Northwest Territory, British Columbia	Fantasque Formation
Fairburn Agate AKA: Tee Pee Canyon Agate, Guernsey Lake Agate				Alternating circular bands of fibrous chalcedony alternating between yellowish brown with a narrower whitish band	Wyoming, South Dakota, Nebraska	Chadron Formation, White River Group
Flathead Quartzite AKA: Alpreston Quartzite				Ranges light reddish to an orangish red.	Wyoming, Montana	Flathead Quartzite Formation
Flattop Butte Chalcedony AKA: Flattop Mesa Chalcedony				Ranges from opaque white to translucent lavender with specks of blue and pink.	Colorado, Wyoming Nebraska	Chadron capstone
Flaxville Quartzite Gravel				Light gray color	Saskatchewan, Montana, North Dakota	Flaxville Formation
Flint Hill Chert AKA fro Florence Chert type D				Wide range of colors including shades of blue and gray, whites, and browns.	Kansas, Oklahoma	Florence Limestone Member of the Barnestone Formation
Flint Hills Quartzite					Kansas, Oklahoma
Florence Chert - Type A AKA: Kay County Chert, Maple City Chert				Banded or "wood grained" and ranges in color from a buff to a yellow gray. Heat treatment produces a red color.	Kansas, Oklahoma, Texas	Florence Limestone Member, Barnestone Formation, Permian Group
Florence Chert - Type B				Ranges in color from a steel gray to a bluish gray with lighter colored splotches or darker colored mottling.	Kansas, Oklahoma, Texas	Florence Limestone Member, Barnestone Formation, Permian Group
Florence Chert - Type C				Homogenous gray	Kansas, Oklahoma, Texas	Florence Limestone Member, Barnestone Formation, Permian Group
Florence Chert - Type D AKA: Flint Hills Chert				Ranges from gray to a buff with many thin bands of darker translucent material.	Kansas, Oklahoma, Texas	Florence Limestone Member, Barnestone Formation, Permian
Florissant Petrified Wood					Colorado	Florissant Formation
Foraker Chert AKA: Four Ace Chert				Light blue color with numerous snow white speckles of fossils.	Kansas, Oklahoma	Foraker Limestone Formation
Fort Union Porcellanite AKA: Powder River Chert				Ranges from most commonly a light gray to a light purple or red.	Montana, Wyoming	Fort Union Formation
Fourmile Gulch Petrified Wood					Wyoming	Bridger Formation
Fremont Chert				Ranges in color including red, pink, purple, buff, brown, yellow, gray, blue, and white.	Central Colorado	Fremont Formation
Gallatin Petrified Forest Wood AKA: Specimen Ridge, Bighorn Peak Petrified Wood				Ranges from reds to yellows with inclusions of milky white. "Wood grain" and rings are present in the material.	Wyoming, Montana (Gallatin Region of Yellowstone)	Sepulcher Formation
Garnet Range Quartzite				Greenish gray color	Montana	Garnet Range Formation, Missoula Group
Gilmore City Chert				Opaque brownish gray	Kansas	Gilmore City Formation
Gilson Gulch Opalescent				Blue and yellow	Colorado
Glacial Pass Concretions AKA: Glacial Pass Siliceous Mudstone				Ranging from dark gray or brown brown to beige, and greyish brown with some purplish brown	British Columbia, Alberta	Fernie Formation
Goose Egg Chert				Ranges from a gray to a dark gray or reddish gray color	Wyoming	Goose Egg Formation
Grand Falls Chert Boone Chert variation				Light gray color and may vary to brown	Kansas	Grand Falls Member of the Boone Formation
Grinnell Argillite				Ranges from a greenish gray or a dark red color	Alberta, Montana, British Columbia	Grinnell Formation of the Belt Series
Grizzly Ridge Chert					Alberta, Manitoba
Gronlid Siltstone				Black in color with a gray shale cortex	Alberta, Saskatchewan, Montana
Gunnison River Chalcedony / Jasper				Light blue chalcedony	Colorado	Dakota Sandstone Formation
Hall Turquoise				Fair blue color with veins of darker material	Colorado
Hand Hills Agate					Alberta
Harabell Porcellanite				Light green tuffaceous porcellanite	Wyoming	Harebell Formation
Hardscrabble Chert				Ranges from a cream to a tan or orange, banded lavender, gray, and purple and solid white chert also occurs.	Central Colorado	Hardscrabble Formation
Hartville Chert AKA:Hartville Uplift Chert, Hartville Uplift Jasper				Ranges from most commonly colors and hues of yellow, orange, red, brown, and purple with black mottling and dendrites common	Colorado, Wyoming, Nebraska, Kansas	Hartville Formation
Hartville Quartzite AKA: Hartville Uplift Quartzite				Ranges from white to a light to medium gray, tan or red, white streaking may be present.	Colorado, Wyoming, Nebraska, Kansas	Hartville Formation
Helena Chert					Montana, Alberta	Helena Limestone Formation
Hells Canyon Chert				Banded and ranges from a tan to purple or gray or brown. Vugs filled with chalcedony or drusy quartz are commonly present	South Dakota
Henry Mountain Peach Agate / Petrified Wood				Petrified wood has colors of yellow, brown, red, white, and black with wood grain or rings commonly present. Agate is a peach color.	Utah
Hilliard Porcellanite				Platy and opaque ranging from a tan to dark brown in color.	Wyoming	Hilliard Formation
Hogback Chalcedony				Ranges from light gray to brown with small lighter colored circles. Mottling may be present	South Dakota, Wyoming
Hogback Quartzite				Ranges from light tan to dark brown.	South Dakota, Wyoming
Holiday Springs Moss Agate				Matrix that ranges from a translucent brown, gray or whitish or an opaque white with black dendritic inclusions	Colorado	White River Group
Holy Cross Turquoise				Blue in color	Colorado
Hot Sulfur Springs Agate / Petrified Wood				Cloudy	Colorado
HS Silcrete AKA: Hard Siliceous Silcrete				Ranges from a dark brown to black with mottled patches of gray.	North Dakota	Camels Butte Member of the Golden Valley Formation
Hunton Chert					Kansas	Hunton Limestone Formation
Irish Rock Chert				Ranges from a light grayish green to a dark blackish green, but may range to hues of caramel or red.	Wyoming
Jack Creek Quartzite				White	Wyoming	Jack Creek Formation
Jack Morrow Hills Petrified Wood					Wyoming
Kalouse Jasper / Petrified Wood				Commonly has concentric banding, ranges from medium brown, yellow, brown, or purple. Rarely bright orangish red or off white occurs.	Colorado	Ingleside Formation, White River Group
Kansas Pipestone				Homogenous medium red color	Kansas
Kelly Canyon Obsidian AKA: Kelley Canyon, Kelley's Canyon Obsidian				Black	Idaho
Kimball Chert				Ranges from tannish off white to tan or light brownish gray. Commonly has dendritic inclusions.	Colorado, Nebraska	Ogallala Formation
King Mine Turquoise AKA: Manassa Turquoise				Ranges from a pale blue to a strong sky blue or bluish green to green with golden and brown color mottling and veinlets and irregular masses.	Colorado
Kingsbury Chert				Dark colored chert	Wyoming	Kingsbury Member of the Wasatch Formation
Kiowa Creek Agate / Carnelian					Colorado
Kiowa Creek Petrified Wood AKA: Bijou Creek Petrified Wood					Colorado
Knee Hills Tuff				Purplish gray weathering to a dark gray to black.	Alberta	Whitemud and Battle Formations
Knife River Flint Knife River Chert, Knife River Chalcedony				Ranges in color from a root beer, tea, coffee, or caramel brown	South Dakota, North Dakota, Saskatchewan, Alberta, Nebraska, Iowa, Minnesota, Montana, Wyoming, Montana, Alberta, Saskatchewan	Eocene Golden Valley Formation
Kootenai Argillite AKA: Kootenay Argillite, Kootenie Argillite				Ranges from a light green to a light gray	Alberta, Montana, Idaho, British Columbia	Kootenai Formation
Kremmling Chert AKA: Troublesome Chert				base of white and hues ranging from light yellow, light gray or light brown, slight mottling or banding and black dendritic inclusions may be present	Colorado	Troublesome Formation
La Garita Creek Chalcedony					Colorado
Lake of the Woods Chert				Ranges from a white mottled with green to a homogenous dark green to black color	Ontario, Saskatchewan, Manitoba, Minnesota, North Dakota	South Kakagi Lake Formation
Lake of the Woods Rhyolite				Ranges in color from a greenish gray to less commonly a gray. Streaks of brown to orangish brown may be present.	Ontario, Saskatchewan, Manitoba, Minnesota, North Dakota
Lake One Dune Chert				Creamy white and gray to a brown	Alberta
Laketown Chert				Light gray	Wyoming, Utah, Idaho	Laketown Dolomite Member of the Guilmette Formation
Lamar Valley Petrified Wood AKA: Amethyst, Mountian, Specimen, Fossil Forest				Ranges from reds to yellows with milky white wood grain, rings are present, outer cortex ranges from chalky whites to pale yellows.	Montana (Lamar Region of Yellowstone)	Lamar Formation
Larkspur Egyptian Jasper / Carnelian / Ribbon Agate / Petrified Wood					Colorado
Last Chance Turquoise					Colorado
Leadville Chert				Ranges from a dark gray to black	Colorado	Leadville Limestone Formation
Leadville Turquoise AKA: Josie May Turquoise					Colorado	Leadville Limestone Formation
Little Heart Chalcedony				Mottled white.	North Dakota
Logan Quarry Chert				Light brownish yellow to a medium yellow. Darker inclusion and veins of quartz / chalcedony may be present.	Montana, Alberta	Jefferson Formation, Madison Group
Lost Canyon Moss Agate				Red moss agate	Wyoming
Louise Falls Orthoquartzite				Quartz rich sandstone forming a orthoquartzite.	Northwest Territories, Alberta	Louise Falls Member of the Hay River Formation.
Luta Chert AKA: Marion Chert, Winfield Chert				Banded chert	Kansas, Oklahoma	Luta Limestone Member of the Winfield Formation
Lysite Agate AKA: Lysaght Agate				Banded and plume agate with fortification lines ranging from reds to browns and white to clear or blue.	Wyoming	Lysite Member of the White River Formation
Madison Chert AKA: Montana Chert				White to a grayish white with black dendritic inclusions.	Wyoming, Montana	Madison Limestone Formation
Malad Obsidian AKA: Dair Creek, Garden Creek Gap, Hawkins, Oneida, Wright Creek Obsidian				Most commonly black, but brownish red mahogany obsidian also occurs.	Idaho
Manassa Turquoise AKA: King's Manassa				Ranges from a brownish green to green with dark brownish yellow to black mottling	Colorado, New Mexico
McNamara Argillite				Red and green	Montana, Idaho	McNamara Formation
Medicine Bow Plume Agate				Translucent milky white chalcedony with dark inclusions forming plumes.	Wyoming
Medicine Peak Quartzite				Ranges from a violet gray to a steel gray.	Wyoming	Medicine Peak Formation
Middle Park Moss Agate / Petrified Wood					Colorado
Miller Peak Argillite				Ranges in color from red to purple (most common) to gray or greenish gray.	Montana	Miller Peak Argillite Member of the McNamara Formation
Minnekahta Chert				Medium brown with a red mesh of hematite and limonite and round quartz inclusions.	Wyoming, South Dakota, Nebraska	Minnekahta Limestone Formation
Minnelusa Chert				Ranges from a tan cream to white or very pale gray or a pale reddish purple.	South Dakota	Minnelusa Formation
Minnelusa Quartzite				Ranges from pinks to reds and browns in color. Banding may be present.	South Dakota	Minnelusa Formation
Missing Link Mountain Quartzite					British Columbia, Alberta
Montana City Jasper				Shades of brown, caramel, and red.	Montana
Morgan Chert AKA: Morgan - Maddison Chert, Morgan Jasper				Has colors of orange to a pumpkin orange, reds, yellowish "mustard" brown to a reddish brown.	Colorado, Utah	Morgan Formation
Morrison Chert AKA: Brushy Basin Chert / Burro Canyon Chert				Commonly mottled and ranges in shaded of maroon, green, tan, and brown.	Colorado, Utah, New Mexico	Burro Canyon Formation / Brushy Basin Member, Morrison Formation
Morrison - Cloverly Porcellanite AKA: Morrison - Clovery Chert				Variegated with colors ranging from gray to blue or red and yellow. Commonly mottled and streaked by fossilized roots and burrows.	Colorado, Wyoming	Morrison and Cloverly formations
Morrison - Cloverly Quartzite AKA: Morrison - Cloverly Orthoquartzite				Ranges from a tan to brown or purple to maroon or gray.	Colorado, Wyoming, New Mexico, Utah	Morrison and Cloverly Formation
Morrison Mudstone				Commonly mottled and ranges in shaded of maroon, green, tan, and brown.	Colorado, Utah, New Mexico	Burro Canyon Formation / Brushy Basin Member, Morrison Formation
Morrison Petrified Wood				Colors of red, yellow, purple, black, gray, brown, and white. Wood grain and rings are commonly present.	Utah, Colorado, New Mexico
Morrison Silicified Sandstone				Commonly mottled and ranges in shaded of maroon, green, tan, and brown.	Colorado, Utah, New Mexico	Brushy Basin Member of the Morrison Formation
Morrison Chert				Commonly mottled and ranges in shaded of maroon, green, tan, and brown.	Colorado, Utah, New Mexico	Burro Canyon Formation / Brushy Basin Member, Morrison Formation
Mount Christie Chert				Ranges from a pale green to a bluish gray or gray weathering to an orangish gray.	Yukon, Northwest Territories, British Columbia	Mount Christie Formation
Mount Sopris Jasper / Jasp-Agate AKA: Sopris Jasper				Ranges from a orangish red to red, dark red, yellow, tan, grayish tan to a dark brown jasper with red to sardonyx jasp agate	Colorado
Muddy Mountain Chert				Brecciated with colors ranging from most commonly a reddish brown, but black, blue and white layers do occur.	Wyoming	Muddy Mountain Chert Member of the Madison Formation
Muldoon Moss Agate				Ranges from a light gray with a light green mossy inclusions.	Idaho
Nehawka Chert Rice Grain Chert, Protozoa Agate, Weeping Water Chert				Ranges from grayish blue to blue with oolitic white specks	Nebraska, Kansas, Iowa	Pennsylvanian Limestone Formation
Neva Chert				White	Kansas, Nebraska, Oklahoma	Neva Limestone Member of the Grenola Formation
Nonda Chert				Ranges from a dark gray to black	Yukon, British Columbia	Nonda Formation
Nordegg Chert AKA: Nordegg Siltstone				Black	Alberta	Nordegg Member of the Fernie Formation
Norquay Chert					Alberta	Mount Head Formation
Northeastern Petrified Wood AKA: Bison Peak, Barronette Peak, Mount Hornaday Petrified Wood				Ranges from reds to yellows with inclusions of milky white. "wood grain" and rings with a cortex ranges chalky whites to pale yellows.	Wyoming, Montana (Northeastern Region of Yellowstone)	Lamar Formation
Northern Quartzite AKA: Alta Quartzite, Polar Quartzite				Ranges from a honey brown to a slightly pale purplish gray color.	Alberta
Nugget Sandstone				Ranges from buff to pink.	Colorado, Utah, Nevada	Chug Water Formation of the Thrust Belt
Obsidian AKA: Volcanic Glass				Black to black with bands of dark reds (mahogany obsidian) or white flakes (snowflake obsidian)	Wyoming, Montana, North Dakota, South Dakota, Alberta, Saskatchewan	Volcanic
Obsidian Cliff Obsidian				Most commonly black, but can range from black to brown, mahogany, gray or green.	Wyoming
Ogallala Orthoquartzite AKA: Bijou Hills Silicified Sediment and Sugar Rock				Colors can vary, but most common colors are light to dark gray, tan, white, pink, maroon, or golden	Colorado, Kansas, Nebraska, Oklahoma, Texas	Ogallala Formation
Ogallala Palm Wood AKA: Petrified Palmwood				Ranges from white to a dark gray with specks.	Kansas, Nebraska	Ogallala Formation
Ogallala Silicified Sediment AKA: Ogallala Chert				Ranges from a buff to a reddish color or gray. Quartz inclusions form speckles in the material.	Nebraska, Kansas, Colorado, Oklahoma, Texas	Ogallala Formation
Opal Hill Opal / Chalcedony				Primarily milky white with black, brown, and pea green occurring	Colorado, Utah
Opal Hill Petrified Wood				Primarily milky white with black, brown, and pea green occurring	Colorado, Utah
Opeche Chert AKA: Opeche Siltstone				Reddish color	South Dakota, Wyoming, Nebraska	Opeche Formation
Osage Chert Osage Undifferentiated Chert				Ranges from a white to light gray or light brown. Occasionally gray to dark gray mottling is present.	Missouri, Illinois, Kansas, Oklahoma, Arkansas	Osage Series
Packsaddle Creek Obsidian AKA: Pack Saddle Obsidian				Black	Idaho
Paha Sapa Chert				Dusty red	South Dakota	Paha Sapa Limestone Formation
Park Point Obsidian				Most commonly mahogany (black with brownish red), but black occurs less often.	Wyoming
Parker Peak Ignimbriote				Black with white crystalline inclusions	Wyoming
Parker Petrified Wood AKA: Cherry Creek Petrified Wood, Moore Ranch Petrified Wood				Ranges from a yellowish tan with clear linear inclusions to a reddish tan with dark tan inclusions.	Colorado
Pawnee Creek Gravel					Nebraska
Pawnee Grassland Quartzite				Ranges in color from a pinkish to a yellowish tan.	Colorado, Nebraska, Wyoming	Pawnee Creek Bed Formation
Peace Point Chert				Mottled and banded gray color	Alberta	Limestone formation
Peace River Chert				Black	British Columbia, Alberta
Peace River Siltstone				Ranges from a dark gray to black	British Columbia, Alberta	Peace River Formation
Peoria Chert AKA: Tahlequah Chert				Primarily white but ranges to a pale yellowish what to a yellowish brown or pink	Oklahoma, Missouri, Arkansas, Kansas	Tahlequah Member of the Moorefield Formation
Petrified Wood AKA: Agatized Wood, Opalized Wood				Vary in color based on the minerals present during the process	North America	Varies
Phosphoria Chert AKA: Tosi Chert, Big Horn Chert				Ranges from colors of red, maroon, purple, orangish red, green, black and white.	Wyoming, Montana, Utah, Idaho	Tosi Member of the Phosphoria Formation
Pilcher Quartzite				Ranges from a pale orangish pink to a moderate red.	Montana, Idaho	Pilcher Creek Formation of the Missoula Group
Pinon Mesa Petrified Wood				Colors of brown, tan and brownish yellow with "wood grain" and rings being present.	Colorado
Platte County Chert				Mottled and ranges from a light purple to a reddish purple. Vugs filled with course darker purple quartz are commonly present.	Wyoming
Plattsburg Chert				Light brown color.	Kansas, Nebraska, Missouri	Plattsburg Limestone Formation
Plattsmouth Fossiliferous Chert Rice Agate				Ranges from a medium to medium dark gray or brownish gray to black. Light brownish fossils form specks.	Iowa and into Nebraska	Plattsmouth Member of the Oread Formation, Virgilian series, Shawnee Group
Poison Creek Agate				Green agate to clear agate with green inclusions	Idaho
Poncha Pass Agate / Jasper				Blue agate	Colorado
Porcellanite Generic type				Ranges from white to brown or various shades of gray	Montana, North Dakota, South Dakota, Wyoming, Alberta, Saskatchewan	Varies
Poison Creek Agate				Green agate to clear agate with green inclusions	Idaho
Portneuf Chert					Idaho	Portneuf Limestone Formation of the Thaynes Group
Powder River Porcellanite					Wyoming, Montana	Powder River Formation
Prairie Agate				Concentric banding and is a marbled mixture of chalcedony and different colors of jasper	Wyoming, South Dakota, Nebraska	Chadron Formation
Prophet Chert				Ranges from a dark gray to black spiculitic to radiolarian chert.	British Columbia, Yukon, Northwest Territories.	Prophet Formation
Pryor Mountain Jasper				Ranges from brown to red.	Montana
Ptarmigan Chert AKA: Manitou Chert				Occurs in colors of pink, red, orange, tan yellow, brown, gray and white. Mottling or speckle or inclusions may also be present.	Colorado	Ptarmigan Chert Member, Manitou Limestone Formation
Purcell Siliceous Siltstone				Ranges from a khaki green to brown, gray or bluish gray with a rusty weathering common.	British Columbia, Idaho, Montana	Belt Series
Quadrant Quartzite				Ranges from white to a pale yellow or pale pink color.	Montana, Wyoming	Quadrant Formation
Quaking Asp Mountain Jasperoid				Light to dark gray agate with banding red, yellowish orange and gray jasp-agate and veins of quartz..	Wyoming
Rainy Butte Chert AKA: Rainy Butte Silicified Wood				Ranges from a dark reddish brown to a dark chocolate brown with yellowish streaking containing fossilized wood	Montana, North Dakota, South Dakota	Sentinel Butte formation
Ramshorn Mountain Jasper				Banded with colors of brown and black.	Montana
Ranger Canyon Chert				Bluish gray with sponge spicules	Alberta	Ranger Canyon Formation
Red Creek Quartzite Uinta Quartzite variant				Very crystalline white quartzite.	Colorado, Utah, Wyoming
Red Deer Siltstone AKA: Paskapoo Chert				Ranges from a dark red to tan color with white macrofossil inclusions.	Alberta	Paskapoo Formation
Red Desert Black Palm Wood				Black	Wyoming
Red Desert Agate / Jasper				Primarily shades of red with shades of white, yellow, yellowish brown, and gray.	Wyoming
Red River Chert				Ranges from white to light gray or light brown and may vary from a solid color to mottled	Manitoba, Ontario, Minnesota, North Dakota, South Dakota
Reed's Spring Chert AKA: Carr Branch Chert				Opaque chert ranging in color from a bluish gray to a light gray or yellowish brown.	Missouri, Arkansas, Oklahoma, Kansas	Reed's Springs formation
Republican River Jasper AKA for Smoky Hills Jasper				Vary in color from a mustard brown or caramel brown to a chalky or creamy white, less commonly red, green, or black does occur, Inclusions and dendrites may be present	Nebraska, Kansas	Smoky Hills Member of the Niobrara Chalk Formation
Rex Chert				Ranges from a brownish red to purple or an ashy gray to black	Utah, Wyoming, Idaho	Rex Chert Member, Phosphoria Limestone Formation
Rhyolite (Generic Type)				Gray to grayish black, flow banding may be present alternating from light to darker gray	North America	Volcanic Activity
Road Creek Agate				A matrix that ranges from ranges in color from white to gray and bluish gray. Sagenite inclusions, aragonitte fans and calcite pseudomorphs may occur.	Idaho
Rooney Chert				Ranges from white to a light whitish gray.	Montana, Idaho	Rooney Chert Member, Madison Limestone Formation
Round Valley Chert				Ranges from gray to a bluish gray.	Colorado	Round Valley Formation
Saint Stephens Stone				Whitish translucent chalcedony with red spots	Colorado
Salt and Pepper Quartzite Northern Quartzite variant				Matrix that ranges from white to light gray, bluish gray or a light tannish brown white with black inclusions	Alberta, Saskatchewan
Salt Works Cloudy Agate / Moss Agate, Petrified Wood, Opalitic Jasper					Colorado
Salt Works Chalcedony				Ranges from a lavender to a blue.	Colorado
San Luis Valley Plume Agate					Colorado
San Rafael Agate / Jasper				Ranges from white to red and yellow	Utah	Brushy Bush Member of the Morrison Formation.
San Rafael Petrified Wood				Colors of brown, black, and white with wood grain and rings present.	Utah	Brushy Bush Member of the Morrison Formation.
Sawatch Quartzite				White to a ferruginous red	Colorado	Sawatch Formation
Schmitt Chert					Wyoming, Montana, Alberta	Mission Canyon Limestone and Lodgepole Limestone formations of the Madison Group
Schroyer Chert AKA: Wreford Type B				Ranges from bluish gray to a gray and may be mottled or splotched with darker gray with speckles of small white fossils	Kansas, Nebraska, Oklahoma	Schroyer Member, Wrenford Limestone Formation
Seminole Mountain Jasp-Agate				Contains alternating layers of brown jasper and grunerite, dark gray quartz, and magnetized black magnetite	Wyoming
Sentinel Butte Porcellanite				Light green color	North Dakota, Montana	Sentinel Butte Shale Member of the Fort Union Formation
Sevenmile Ridge Chert Tiger Chert variation				Most commonly very dark brown to black, but may range to a medium brown with a light brown mottling.	Wyoming	Bridger Formation
Sheldon Chert				Translucent to opaque chert ranging from a light to dark gray or yellowish brown and pinkish brown. Densely filled with fossil fragments	Iowa, Nebraska	Sheldon Member of the Topeka Formation, Shawnee Group
Sheep Canyon Dendritic Jasper				Ranges from a yellowish brown with black speckles to a light grayish brown with red speckles	Wyoming
Sheep Creek Quartzite				Most commonly tan to cream color with light gray occurring and less often dark gray, white or red. Banding is commonly present	Utah	Uinta Quartzite Formation
Shirley Basin Petrified Wood / Jasp-Agate				Wood has colors of white to brown to black. The jasp-agate is a pink breccia matrix cemented with a reddish brown or gray to black.	Wyoming	Windy River Formation
Silicified Dinosaur Bone					Colorado, Wyoming
Silicified Peat					Alberta
Sioux Jasper \AKA: Sioux Falls Jasper				Ranges in color from a brownish yellow to red	South Dakota, Iowa, Nebraska, Minnesota	Sioux Formation
Sioux Quartzite AKA: Redstone Quartzite				Ranges from a light grayish tan to a medium grayish brown.	South Dakota, Iowa, Nebraska, Minnesota	Sioux Formation
Six Mile Hill Petrified Wood					Wyoming
Slater Agate / Chalcedony				White outer coating, interior dark gray to black agate surrounding a milky white center with small black inclusions.	Wyoming	Guernsey Formation of the Hartville Uplift
Smoky Hills Jasper AKA: Alma, Graham, Niobrara, Republican River Jasper				Vary in color from a mustard brown or caramel brown to a chalky or creamy white, less commonly red, green, or black does occur, Inclusions and dendrites may be present	Kansas, Nebraska	Smoky Hills Member of the Niobrara Chalk Formation
South Bend Chert				Ranges from a light gray to a light bluish gray, concretions are commonly present.	Nebraska, Kansas	South Bend Limestone Member of the Stanton Limestone Formation
South Everson Chert				Mottled or a breccia and ranges in from most commonly a red to a yellowish red or yellow and yellowish brown to brown.	Montana
Sowbelly Agate				Quarter inch alternating bands of brown, purplish brown and white. Has light purple, blue, brown, amethyst with galena or silver inclusions.	Colorado
Spanish Diggings Agate				Mottled and banded red gray and red.	Wyoming	Fall River and Lamoka Formation of the Inyan Kara Group
Spanish Diggings Chert				Mottled and ranges from a brown to gray.	Wyoming	Fall River and Lamoka Formation of the Inyan Kara Group
Spanish Diggings Dendritic Jasper				Greenish yellow color with dark dendritic inclusions.	Wyoming	Fall River and Lamoka Formation of the Inyan Kara Group
Spanish Diggings Quartzite AKA: Fall River Quartzite and Lamoka Quartzite				Range from a medium to very light shades of brown, gray, and purple or purplish gray, may be homogenous to variegated or banded	Wyoming, South Dakota, Nebraska	Fall River and Lamoka Formation of the Inyan Kara Group
Spanish Diggings Red Breccia				Brecciated with shade of red.	Wyoming	Fall River and Lamoka Formation of the Inyan Kara Group
Spanish Point Agate				Ranges from white to a light tannish white or grayish white with dark dendritic starburst and inclusions.	Wyoming	White River Formation
Spearfish Chert				Ranges from a grayish red to purple	South Dakota, Nebraska, Wyoming	Spearfish Limestone Formation
Spring Branch Chert				Primarily a medium gray chert with darker fossil inclusions. Bluish gray chalcedony vugs may be present.	Iowa, Nebraska	Spring Branch Limestone of the Lecompton Formation
Spring Hill Chert				Strongly mottled and ranges from light to dark gray with dark speckles being present.	Kansas, Missouri, Iowa, Nebraska	Spring Hill Member, Plattsburg Limestone Formation
St. Stephens Stone Banded Agate					Colorado
Stefoinite Brecciated Jasper				Brecciated with shades of tan, brown, and white.	Wyoming
Stoner Chert Type A and B				Ranges from light to medium gray or a grayish tan with white veins.	Iowa, Nebraska, Missouri, Kansas	Stoner Member of the Stanton Formation, Lansing Group
Summerville Chert				Two variations. One is black chert and the other is a white opalitic chert.	Colorado, Utah	Summerville Formation
Swan Peak Quartzite				Ranges from white to gray	Utah, Idaho, Nevada	Swan Peak Formation
Swan River Chert				Ranges from a creamy white to gray, pink to a rust, or pale yellow to deep orange, commonly has banding	Ontario, Manitoba, Saskatchewan, Minnesota, North Dakota, South Dakota, Iowa, Montana	Souris River Formation, Point Wilks Member
Swauger Quartzite				Ranges from purple or lavender to almost pure white.	East central Idaho	Belt Series
Sweetwater Moss Agate				Brown cortex with a light gray to blue matrix and black dendritic inclusions.	Wyoming	Split Rock Formation
Table Mountain Chert / Jasper				Exhibits orange and red coloring with clear veins	Colorado	Troublesome Formation
Table Mountain Opal				Ranges from red to a reddish brown or brownish orange.	Colorado
Table Mountain Petrified Wood AKA: Green Mountain Petrified Wood					Colorado
Taylor Bed Silcrete AKA: Taylor Bed Chert / Taylor Bed Quartzite				Ranges from a gray to light tan commonly iron stained. Remnants of wood and cattails are commonly present	Montana, South Dakota	Dean Member of the Golden Valley formation
Tensleep Quartzite				Most commonly a light tan to tan, but grays, greens, reds and pinks do occur.	Wyoming	Tensleep Sandstone Formation
Teredo Petrified Wood				Primarily black or dark gray with prehistoric Teredo (worm shaped mollusk) boring or worming through the wood.	North Dakota	Cannonball Formation
Tertiary Hills Clinker AKA: Tertiary Hills Welded Tuff, Keele River Obsidian				Ranges in color from white to grey, lower quality light brown, red, and purple are seen.	Alberta, British Columbia, Yukon, Northwest Territories
Teton Chert				White	Wyoming	Teton Formation
Teton Pass Obsidian AKA: Crescent H Obsidian				Ranges from black to gray and is banded.	Wyoming
Thirtyone Mile Mountain Chalcedony				Light blue banded chalcedony	Colorado
Thompson Agate / Jasper					Utah
Three Mile Chert Wreford Chert Variant AKA: Wreford Chert type A, Fourmile Chert				Yellowish brown	Kansas, Oklahoma	Threemile Limestone Member, Wreford Limestone Formation, Permian Group
Tiger Chert AKA: Bridger Basin, Green River, Oil Chert, Zebra Chert, Shavetail Chert				Primarily dark brown with wide tan banding. If the material is smaller, the tan could be primary with the darker brown bands.	Colorado, Wyoming, Utah	Pine Springs
Tin Cup Jasper				Jasper breccia or banded with angular fragments of ranges from deep red to a dark brown, butterscotch yellowish brown	Wyoming
Tom Miner Basin Wood				Ranges from black to tan or brown with white rings or wood grain. White chalcedony inclusions and reds colors may be present.	Montana
Tomichi Chert				Mottled bluish gray color weathering brown.	Colorado	Tomichi Limestone Formation
Tongue River Silicified Sediment AKA: Tongue River Silica				Grayish brown sediment, pseudoquartzite, or arenaceous chert	North Dakota, South Dakota, Montana, Nebraska, Wyoming, Minnesota, Iowa	Slope / Bullion Creek formation
Toronto Chert				Homogenous ranging from a white to a pale brown or yellowish brown.	Kansas and into Oklahoma, Iowa, Nebraska, and Missouri	Toronto Limestone Member, Oread Formation of the Shawnee Group
Torrey Agate / Jasper / Petrified Wood				Petrified wood has shades of tan and gray with wood grain and rings commonly present.	Utah
Tower Region Petrified Wood AKA: Yancy's Forest, Roosevelt Lodge Petrified Wood				Ranges from reds to yellows with inclusions of milky white. "Wood grain" and rings are present in the material.	Wyoming, Montana (Tower region of Yellowstone)	Lamar Formation
Trapper Creek Agate				Colors of brown to to cream with dendritic inclusions.	Wyoming	Madison Limestone Formation
Trout Creek Chert / Jasper				Ranges from a dusky red to a yellowish brown with inclusions or lines forming intricate patters are commonly present..	Colorado	Manitou or the Fremont Formation
Tuff AKA: Solidified Volcanic Ash				Contains greater than 75 volcanic ash and ranges from white to tan, gray or pink.	North America	Volcanic activity
Turritella Agate AKA for Elimia Agate				Black to brownish gray or brownish black matrix with light gray snail shells.	Colorado, Wyoming	Green River Formation
Twin Creek Agate				Irregular banded with red and golden yellow flame jasper.	Wyoming	Amsden or Phosphoria Formations
Upper Lamar Petrified Wood AKA: Miller Creek, Cache Creek, Cache Mountain, Abiathar Peak, The Thunderer Petrified Wood				Ranges from reds to yellows with inclusions of milky white. "Wood grain" and rings are present in the material.	Montana (Upper Lamar Valley in Yellowstone)	Lamar Formation
Upper Rio Grande Jasper / Opal				Mottled yellow color with inclusions of varicolored opal.	Colorado
Vanochen Chert					Montana, Alberta
Wagon Wheel Gap Carnelian				Clear and variegated	Colorado
Wamsutter Oolitic Chert AKA: Green River Oolitic Chert				Ranges from an off white to a medium brown with white oolitic specks throughout the material	Wyoming, Colorado	Green River Formation
Westerville Chert				Ranges from homogeneous to mottled pale brown to a light yellowish brown or brownish yellow with thin bands may be present.	Missouri, Kansas	Westerville Limestone Member of the Cherryvale Shale Formation
Whiskey Basin Petrified Wood					Wyoming	Bridger Formation
Whiskey Butte Chert				Algal chert ranging from black to dark brown or tan with light blue opal inclusions.	Wyoming	Laney Member of the Green River Formation
White River Group Silicate Generic type				Ranges from light to medium gray, to a light brown, pink, blue or lavender with inclusions, splotches,mottling.	Wyoming, North Dakota, South Dakota, Nebraska, eastern Montana and northeastern Colorado.	White River Group
White River Group Plate Chalcedony AKA: Badlands Plate Chalcedony				Quarter inch thick ranging from clear to milky white with a rough milky white cortex	South Dakota, Nebraska	White River Group
Whitewood Chert AKA: Deadwood Chert				Colors of light gray, pinks and reds, and tan.	South Dakota, Wyoming	Whitewood Limestone (dolomite) Formation
Wiggins Fork Petrified Wood AKA: DeBois Petrified Wood				Colors of red, brown, gray white and green. Banding and wood grain is present.	Wyoming	Wiggins Formation
Willow Creek Chalcedony / Carnelian					Colorado
Willow Creek Ribbon Jasper					Colorado
Williams Canyon Chert				Ranges from grayish white to gray.	Colorado	Williams Canyon Limestone Formation
Williams Fork Moss Agate					Colorado
Windy Ridge Quartzite				Ranges in color from a yellowish tan to a rosy pink or a grayish silver. Gray undertones may be present.	Colorado	Dakota Quartzite
Winterset Chert AKA: Fusulinid Chert, Zebra Chert				Primarily homogenous, ranging to mottled or layered, ranging from a light to dark gray or brownish gray, opaque may have a "zebra" appearance	Nebraska, Iowa, Missouri, Kansas	Winterset Limestone Member of the Dennis Limestone Formation, Kansas City Group
Wolf Creek Pass Sagenitic Agate					Colorado	Treasure Island Rhyolite Formation
Woodhurst Chert Madison Chert variant				Ranges from a dark gray to almost black	Montana	Woodhurst Member of the Madison Limestone Formation
Wreford Chert				Ranges from a buff to tan or grayish tan to a bluish gray to gray. Mottling or banding may be present.	Kansas, Oklahoma	Wrenford Limestone Formation
Yellow Cat Redwood				Red limb casts without any trace of wood structure	Utah
Yellow Tree Jasper				Ranges from a yellow to a light brown or light orange with black "tree like" dendritic inclusions.	Wyoming
Youngsite Agate AKA: Hartsville Uplift Agate				Ranges in color from a yellowish tan to a rosy pink or a grayish silver. Gray undertones may be present.	Wyoming, Nebraska	Guernsey Limestone Formation