Kimberlite
Kimberlite catalog
Own a genuine piece of Colorado's volcanic past with kimberlite sourced from the Sloan Diatreme in Larimer County, part of the State Line Kimberlite District.
Available Kimberlite listings

Sloan Kimberlite with Chrome Diopside — 452g
Kimberlite
Specimen: KIMBERLITE 452 grams, un-cut Contains an emerald green chrome diopside xenocryst $226.00 Location: Sloan Ranch Diatreme, State Line District, Colorado This sample of kimberlite was collected from the Sloan Diatreme in northern Larimer County, Colorado. The Sloan Ranch Complex consists of a series of six diamond bearing volcanic pipes located in the State Line Kimberlite District. Several companies recovered more than 30,000 diamonds from bulk samples in the Sloan 1 and Sloan 2 diatremes in the 1980s and 1990s averaging 12 to 18 carats per 100 metric tons of kimberlite. The largest diamond recovered was a 5.51 carat gemstone. This site was determined to be sub-economic, however, and was never mined commercially. I obtained samples of this material in 2005 while supervising reclamation activities at the site. The Kelsey Lake Mine, located a few miles north of the Sloan diatreme, produced diamonds between 1996 and 1998 and is the only commercial diamond mine to have operated in the United States. Both the Kelsey Lake Mine and the Sloan exploration openings have been backfilled and reclaimed and the respective landowners do not allow visitors. This sample of kimberlite comes from an exploration adit driven in the Sloan 2 diatreme in the 1990s. It is ‘as found’ (no cuts), weighs 452 grams, contains a chrome diopside xenocryst, and measures 3.0” x 2.0”x 2.5.” Kimberlite occurs in diatremes, vertical volcanic pipes formed by powerful, gas-driven explosive eruptions. In addition to diamonds, the Sloan kimberlite contains lower crustal/mantle indicator minerals including ilmenite, pyrope garnet, chrome diopside and xenoliths of peridotite, dunite, and eclogite. It also contains abundant xenoliths of early Paleozoic rocks including fossiliferous limestone and pre-Cambrian rocks. There are numerous articles about kimberlite on the internet. Here are two good publications: Overview of the Sloan 1 & 2 Diamondiferous Kimberlite, Colorado-Wyoming State Line District, compiled by W. Dan Hausel, 1996 Industrial Minerals Forum Field Trip – Mineral Report MRS96-4, 1996 Diamonds and Mantle Source Rocks in the Wyoming Craton with a Discussion of other U. S, Occurrences, by W Dan Hausel, Wyoming Geological Survey Report of Investigations No. 53, 1998.
Price
$226.00

Sloan Kimberlite — 207g
Kimberlite
Specimen: KIMBERLITE 207 grams, cut on two sides $51.00 Location: Sloan Ranch Diatreme, State Line District, Colorado This sample of kimberlite was collected from the Sloan Diatreme in northern Larimer County, Colorado. The Sloan Ranch Complex consists of a series of six diamond bearing volcanic pipes located in the State Line Kimberlite District. Several companies recovered more than 30,000 diamonds from bulk samples in the Sloan 1 and Sloan 2 diatremes in the 1980s and 1990s averaging 12 to 18 carats per 100 metric tons of kimberlite. The largest diamond recovered was a 5.51 carat gemstone. This site was determined to be sub-economic, however, and was never mined commercially. I obtained samples of this material in 2005 while supervising reclamation activities at the site. The Kelsey Lake Mine, located a few miles north of the Sloan diatreme, produced diamonds between 1996 and 1998 and is the only commercial diamond mine to have operated in the United States. Both the Kelsey Lake Mine and the Sloan exploration openings have been backfilled and reclaimed and the respective landowners do not allow visitors. This sample of kimberlite comes from an exploration adit driven in the Sloan 2 diatreme in the 1990s. It is cut on two sides, weighs 207 grams, and measures 3.0” x 1.5”x 1.6.” Kimberlite occurs in diatremes, vertical volcanic pipes formed by powerful, gas-driven explosive eruptions. In addition to diamonds, the Sloan kimberlite contains lower crustal/mantle indicator minerals including ilmenite, pyrope garnet, chrome diopside and xenoliths of peridotite, dunite, and eclogite. It also contains abundant xenoliths of early Paleozoic rocks including fossiliferous limestone and pre-Cambrian rocks. There are numerous articles about kimberlite on the internet. Here are two good publications: Overview of the Sloan 1 & 2 Diamondiferous Kimberlite, Colorado-Wyoming State Line District, compiled by W. Dan Hausel, 1996 Industrial Minerals Forum Field Trip – Mineral Report MRS96-4, 1996 Diamonds and Mantle Source Rocks in the Wyoming Craton with a Discussion of other U. S, Occurrences, by W Dan Hausel, Wyoming Geological Survey Report of Investigations No. 53, 1998.
Price
$51.00

Sloan Kimberlite & Diamond Set — 257g
Kimberlite
Specimen: KIMBERLITE 257 grams, cut on two sides and comes with a small rough diamond from South Africa $84.00 Location: Sloan Ranch Diatreme, State Line District, Colorado This sample of kimberlite was collected from the Sloan Diatreme in northern Larimer County, Colorado. The Sloan Ranch Complex consists of a series of six diamond bearing volcanic pipes located in the State Line Kimberlite District. Several companies recovered more than 30,000 diamonds from bulk samples in the Sloan 1 and Sloan 2 diatremes in the 1980s and 1990s averaging 12 to 18 carats per 100 metric tons of kimberlite. The largest diamond recovered was a 5.51 carat gemstone. This site was determined to be sub-economic, however, and was never mined commercially. I obtained samples of this material in 2005 while supervising reclamation activities at the site. The Kelsey Lake Mine, located a few miles north of the Sloan diatreme, produced diamonds between 1996 and 1998 and is the only commercial diamond mine to have operated in the United States. Both the Kelsey Lake Mine and the Sloan exploration openings have been backfilled and reclaimed and the respective landowners do not allow visitors. This sample of kimberlite comes from an exploration adit driven in the Sloan 2 diatreme in the 1990s. It is cut on two sides, weighs 257 grams, and measures 2.0” x 1.5”x 1.5” It comes with a small rough diamond from South Africa. Kimberlite occurs in diatremes, vertical volcanic pipes formed by powerful, gas-driven explosive eruptions. In addition to diamonds, the Sloan kimberlite contains lower crustal/mantle indicator minerals including ilmenite, pyrope garnet, chrome diopside and xenoliths of peridotite, dunite, and eclogite. It also contains abundant xenoliths of early Paleozoic rocks including fossiliferous limestone and pre-Cambrian rocks. There are numerous articles about kimberlite on the internet. Here are two good publications: Overview of the Sloan 1 & 2 Diamondiferous Kimberlite, Colorado-Wyoming State Line District, compiled by W. Dan Hausel, 1996 Industrial Minerals Forum Field Trip – Mineral Report MRS96-4, 1996 Diamonds and Mantle Source Rocks in the Wyoming Craton with a Discussion of other U. S, Occurrences, by W Dan Hausel, Wyoming Geological Survey Report of Investigations No. 53, 1998.
Price
$84.00

Sloan Kimberlite & Diamond Set — 475g
Kimberlite
Specimen: KIMBERLITE 475 grams, cut on two sides and comes with a small rough diamond from South Africa $138.00 Location: Sloan Ranch Diatreme, State Line District, Colorado This sample of kimberlite was collected from the Sloan Diatreme in northern Larimer County, Colorado. The Sloan Ranch Complex consists of a series of six diamond bearing volcanic pipes located in the State Line Kimberlite District. Several companies recovered more than 30,000 diamonds from bulk samples in the Sloan 1 and Sloan 2 diatremes in the 1980s and 1990s averaging 12 to 18 carats per 100 metric tons of kimberlite. The largest diamond recovered was a 5.51 carat gemstone. This site was determined to be sub-economic, however, and was never mined commercially. I obtained samples of this material in 2005 while supervising reclamation activities at the site. The Kelsey Lake Mine, located a few miles north of the Sloan diatreme, produced diamonds between 1996 and 1998 and is the only commercial diamond mine to have operated in the United States. Both the Kelsey Lake Mine and the Sloan exploration openings have been backfilled and reclaimed and the respective landowners do not allow visitors. This sample of kimberlite comes from an exploration adit driven in the Sloan 2 diatreme in the 1990s. It is cut on two sides, weighs 475 grams, and measures 3.3” x 1.6”x 1.8” It comes with a small rough diamond from South Africa. Kimberlite occurs in diatremes, vertical volcanic pipes formed by powerful, gas-driven explosive eruptions. In addition to diamonds, the Sloan kimberlite contains lower crustal/mantle indicator minerals including ilmenite, pyrope garnet, chrome diopside and xenoliths of peridotite, dunite, and eclogite. It also contains abundant xenoliths of early Paleozoic rocks including fossiliferous limestone and pre-Cambrian rocks. There are numerous articles about kimberlite on the internet. Here are two good publications: Overview of the Sloan 1 & 2 Diamondiferous Kimberlite, Colorado-Wyoming State Line District, compiled by W. Dan Hausel, 1996 Industrial Minerals Forum Field Trip – Mineral Report MRS96-4, 1996 Diamonds and Mantle Source Rocks in the Wyoming Craton with a Discussion of other U. S, Occurrences, by W Dan Hausel, Wyoming Geological Survey Report of Investigations No. 53, 1998.
Price
$138.00

Sloan Kimberlite — 424g
Kimberlite
Specimen: KIMBERLITE 424 grams, cut on three sides $106.00 Location: Sloan Ranch Diatreme, State Line District, Colorado This sample of kimberlite was collected from the Sloan Diatreme in northern Larimer County, Colorado. The Sloan Ranch Complex consists of a series of six diamond bearing volcanic pipes located in the State Line Kimberlite District. Several companies recovered more than 30,000 diamonds from bulk samples in the Sloan 1 and Sloan 2 diatremes in the 1980s and 1990s averaging 12 to 18 carats per 100 metric tons of kimberlite. The largest diamond recovered was a 5.51 carat gemstone. This site was determined to be sub-economic, however, and was never mined commercially. I obtained samples of this material in 2005 while supervising reclamation activities at the site. The Kelsey Lake Mine, located a few miles north of the Sloan diatreme, produced diamonds between 1996 and 1998 and is the only commercial diamond mine to have operated in the United States. Both the Kelsey Lake Mine and the Sloan exploration openings have been backfilled and reclaimed and the respective landowners do not allow visitors. This sample of kimberlite comes from an exploration adit driven in the Sloan 2 diatreme in the 1990s. It is cut on three sides, weighs 424 grams, and measures 3.0” x 2.5”x 1.2.” Kimberlite occurs in diatremes, vertical volcanic pipes formed by powerful, gas-driven explosive eruptions. In addition to diamonds, the Sloan kimberlite contains lower crustal/mantle indicator minerals including ilmenite, pyrope garnet, chrome diopside and xenoliths of peridotite, dunite, and eclogite. It also contains abundant xenoliths of early Paleozoic rocks including fossiliferous limestone and pre-Cambrian rocks. There are numerous articles about kimberlite on the internet. Here are two good publications: Overview of the Sloan 1 & 2 Diamondiferous Kimberlite, Colorado-Wyoming State Line District, compiled by W. Dan Hausel, 1996 Industrial Minerals Forum Field Trip – Mineral Report MRS96-4, 1996 Diamonds and Mantle Source Rocks in the Wyoming Craton with a Discussion of other U. S, Occurrences, by W Dan Hausel, Wyoming Geological Survey Report of Investigations No. 53, 1998.
Price
$106.00

Sloan Kimberlite — 320g
Kimberlite
Specimen: KIMBERLITE 320 grams, cut on two sides $80.00 Location: Sloan Ranch Diatreme, State Line District, Colorado This sample of kimberlite was collected from the Sloan Diatreme in northern Larimer County, Colorado. The Sloan Ranch Complex consists of a series of six diamond bearing volcanic pipes located in the State Line Kimberlite District. Several companies recovered more than 30,000 diamonds from bulk samples in the Sloan 1 and Sloan 2 diatremes in the 1980s and 1990s averaging 12 to 18 carats per 100 metric tons of kimberlite. The largest diamond recovered was a 5.51 carat gemstone. This site was determined to be sub-economic, however, and was never mined commercially. I obtained samples of this material in 2005 while supervising reclamation activities at the site. The Kelsey Lake Mine, located a few miles north of the Sloan diatreme, produced diamonds between 1996 and 1998 and is the only commercial diamond mine to have operated in the United States. Both the Kelsey Lake Mine and the Sloan exploration openings have been backfilled and reclaimed and the respective landowners do not allow visitors. This sample of kimberlite comes from an exploration adit driven in the Sloan 2 diatreme in the 1990s. It is cut on two sides, weighs 320 grams, and measures 3.0” x 1.4”x 2.7” Kimberlite occurs in diatremes, vertical volcanic pipes formed by powerful, gas-driven explosive eruptions. In addition to diamonds, the Sloan kimberlite contains lower crustal/mantle indicator minerals including ilmenite, pyrope garnet, chrome diopside and xenoliths of peridotite, dunite, and eclogite. It also contains abundant xenoliths of early Paleozoic rocks including fossiliferous limestone and pre-Cambrian rocks. There are numerous articles about kimberlite on the internet. Here are two good publications: Overview of the Sloan 1 & 2 Diamondiferous Kimberlite, Colorado-Wyoming State Line District, compiled by W. Dan Hausel, 1996 Industrial Minerals Forum Field Trip – Mineral Report MRS96-4, 1996 Diamonds and Mantle Source Rocks in the Wyoming Craton with a Discussion of other U. S, Occurrences, by W Dan Hausel, Wyoming Geological Survey Report of Investigations No. 53, 1998.
Price
$80.00

Sloan Kimberlite — 155g
Kimberlite
Specimen: KIMBERLITE 155 grams, cut on one side $38.00 Location: Sloan Ranch Diatreme, State Line District, Colorado This sample of kimberlite was collected from the Sloan Diatreme in northern Larimer County, Colorado. The Sloan Ranch Complex consists of a series of six diamond bearing volcanic pipes located in the State Line Kimberlite District. Several companies recovered more than 30,000 diamonds from bulk samples in the Sloan 1 and Sloan 2 diatremes in the 1980s and 1990s averaging 12 to 18 carats per 100 metric tons of kimberlite. The largest diamond recovered was a 5.51 carat gemstone. This site was determined to be sub-economic, however, and was never mined commercially. I obtained samples of this material in 2005 while supervising reclamation activities at the site. The Kelsey Lake Mine, located a few miles north of the Sloan diatreme, produced diamonds between 1996 and 1998 and is the only commercial diamond mine to have operated in the United States. Both the Kelsey Lake Mine and the Sloan exploration openings have been backfilled and reclaimed and the respective landowners do not allow visitors. This sample of kimberlite comes from an exploration adit driven in the Sloan 2 diatreme in the 1990s. It is cut on two sides, weighs 155 grams, and measures 2.0” x 2.0”x 1.2.” Kimberlite occurs in diatremes, vertical volcanic pipes formed by powerful, gas-driven explosive eruptions. In addition to diamonds, the Sloan kimberlite contains lower crustal/mantle indicator minerals including ilmenite, pyrope garnet, chrome diopside and xenoliths of peridotite, dunite, and eclogite. It also contains abundant xenoliths of early Paleozoic rocks including fossiliferous limestone and pre-Cambrian rocks. There are numerous articles about kimberlite on the internet. Here are two good publications: Overview of the Sloan 1 & 2 Diamondiferous Kimberlite, Colorado-Wyoming State Line District, compiled by W. Dan Hausel, 1996 Industrial Minerals Forum Field Trip – Mineral Report MRS96-4, 1996 Diamonds and Mantle Source Rocks in the Wyoming Craton with a Discussion of other U. S, Occurrences, by W Dan Hausel, Wyoming Geological Survey Report of Investigations No. 53, 1998.
Price
$38.00

Sloan Kimberlite — 258g
Kimberlite
Specimen: KIMBERLITE 258 grams, cut on two sides and comes with a small rough diamond from South Africa $64.00 Location: Sloan Ranch Diatreme, State Line District, Colorado This sample of kimberlite was collected from the Sloan Diatreme in northern Larimer County, Colorado. The Sloan Ranch Complex consists of a series of six diamond bearing volcanic pipes located in the State Line Kimberlite District. Several companies recovered more than 30,000 diamonds from bulk samples in the Sloan 1 and Sloan 2 diatremes in the 1980s and 1990s averaging 12 to 18 carats per 100 metric tons of kimberlite. The largest diamond recovered was a 5.51 carat gemstone. This site was determined to be sub-economic, however, and was never mined commercially. I obtained samples of this material in 2005 while supervising reclamation activities at the site. The Kelsey Lake Mine, located a few miles north of the Sloan diatreme, produced diamonds between 1996 and 1998 and is the only commercial diamond mine to have operated in the United States. Both the Kelsey Lake Mine and the Sloan exploration openings have been backfilled and reclaimed and the respective landowners do not allow visitors. This sample of kimberlite comes from an exploration adit driven in the Sloan 2 diatreme in the 1990s. It is cut on two sides, weighs 258 grams, and measures 3.0” x 1.5”x 1.” It comes with a small rough diamond from South Africa. Kimberlite occurs in diatremes, vertical volcanic pipes formed by powerful, gas-driven explosive eruptions. In addition to diamonds, the Sloan kimberlite contains lower crustal/mantle indicator minerals including ilmenite, pyrope garnet, chrome diopside and xenoliths of peridotite, dunite, and eclogite. It also contains abundant xenoliths of early Paleozoic rocks including fossiliferous limestone and pre-Cambrian rocks. There are numerous articles about kimberlite, diatremes, and the State Line District on the internet. Here are two good publications: Overview of the Sloan 1 & 2 Diamondiferous Kimberlite, Colorado-Wyoming State Line District, compiled by W. Dan Hausel, 1996 Industrial Minerals Forum Field Trip – Mineral Report MRS96-4, 1996 Diamonds and Mantle Source Rocks in the Wyoming Craton with a Discussion of other U. S, Occurrences, by W Dan Hausel, Wyoming Geological Survey Report of Investigations No. 53, 1998.
Price
$64.00

Colorado Sloan Kimberlite 76g Chrome Diopside + Rough South African Diamond
Kimberlite
Specimen: KIMBERLITE 76 grams Contains an emerald green chrome diopside xenocryst and comes with a small rough diamond from South Africa $58.00 Location: Sloan Ranch Diatreme, State Line District, Colorado This sample of kimberlite was collected from the Sloan Diatreme in northern Larimer County, Colorado. The Sloan Ranch Complex consists of a series of six diamond bearing volcanic pipes located in the State Line Kimberlite District. Several companies recovered more than 30,000 diamonds from bulk samples in the Sloan 1 and Sloan 2 diatremes in the 1980s and 1990s averaging 12 to 18 carats per 100 metric tons of kimberlite. The largest diamond recovered was a 5.51 carat gemstone. This site was determined to be sub-economic, however, and was never mined commercially. I obtained samples of this material in 2005 while supervising reclamation activities at the site. The Kelsey Lake Mine, located a few miles north of the Sloan diatreme, produced diamonds between 1996 and 1998 and is the only commercial diamond mine to have operated in the United States. Both the Kelsey Lake Mine and the Sloan exploration openings have been backfilled and reclaimed and the respective landowners do not allow visitors. This sample of kimberlite comes from an exploration adit driven in the Sloan 2 diatreme in the 1990s. It is cut on one side, weighs 76 grams, and measures 1.0” x 1.0”x 1.5.” It contains a chrome diopside xenocryst and comes with a small rough diamond from South Africa. Kimberlite occurs in diatremes, vertical volcanic pipes formed by powerful, gas-driven explosive eruptions. In addition to diamonds, the Sloan kimberlite contains lower crustal/mantle indicator minerals including ilmenite, pyrope garnet, chrome diopside and xenoliths of peridotite, dunite, and eclogite. It also contains abundant xenoliths of early Paleozoic rocks including fossiliferous limestone and pre-Cambrian rocks. There are numerous articles about kimberlite on the internet. Here are two good publications: Overview of the Sloan 1 & 2 Diamondiferous Kimberlite, Colorado-Wyoming State Line District, compiled by W. Dan Hausel, 1996 Industrial Minerals Forum Field Trip – Mineral Report MRS96-4, 1996 Diamonds and Mantle Source Rocks in the Wyoming Craton with a Discussion of other U. S, Occurrences, by W Dan Hausel, Wyoming Geological Survey Report of Investigations No. 53, 1998.
Price
$58.00
Sold OutSloan Kimberlite & Diamond Set — Chrome Diopside 192g
Kimberlite
Specimen: KIMBERLITE 192 grams Contains an emerald green chrome diopside xenocryst and comes with a small rough diamond from South Africa $78.00 Location: Sloan Ranch Diatreme, State Line District, Colorado This sample of kimberlite was collected from the Sloan Diatreme in northern Larimer County, Colorado. The Sloan Ranch Complex consists of a series of six diamond bearing volcanic pipes located in the State Line Kimberlite District. Several companies recovered more than 30,000 diamonds from bulk samples in the Sloan 1 and Sloan 2 diatremes in the 1980s and 1990s averaging 12 to 18 carats per 100 metric tons of kimberlite. The largest diamond recovered was a 5.51 carat gemstone. This site was determined to be sub-economic, however, and was never mined commercially. I obtained samples of this material in 2005 while supervising reclamation activities at the site. The Kelsey Lake Mine, located a few miles north of the Sloan diatreme, produced diamonds between 1996 and 1998 and is the only commercial diamond mine to have operated in the United States. Both the Kelsey Lake Mine and the Sloan exploration openings have been backfilled and reclaimed and the respective landowners do not allow visitors. This sample of kimberlite comes from an exploration adit driven in the Sloan 2 diatreme in the 1990s. It is cut on two sides, weighs 192 grams, and measures 3.0” x 1.5”x 1.” It contains a chrome diopside xenocryst and comes with a small rough diamond from South Africa. Kimberlite occurs in diatremes, vertical volcanic pipes formed by powerful, gas-driven explosive eruptions. In addition to diamonds, the Sloan kimberlite contains lower crustal/mantle indicator minerals including ilmenite, pyrope garnet, chrome diopside and xenoliths of peridotite, dunite, and eclogite. It also contains abundant xenoliths of early Paleozoic rocks including fossiliferous limestone and pre-Cambrian rocks. There are numerous articles about kimberlite on the internet. Here are two good publications: Overview of the Sloan 1 & 2 Diamondiferous Kimberlite, Colorado-Wyoming State Line District, compiled by W. Dan Hausel, 1996 Industrial Minerals Forum Field Trip – Mineral Report MRS96-4, 1996 Diamonds and Mantle Source Rocks in the Wyoming Craton with a Discussion of other U. S, Occurrences, by W Dan Hausel, Wyoming Geological Survey Report of Investigations No. 53, 1998.
Availability
Sold Out
Sold OutSloan Kimberlite with Garnet Xenocryst 214g
Kimberlite
This kimberlite was collected from the Sloan Diatreme in northern Larimer County, Colorado. The Sloan Ranch Complex consists of six diamond-bearing volcanic pipes in the State Line Kimberlite District. In the 1980s and 1990s, bulk sampling of Sloan 1 and Sloan 2 recovered more than 30,000 diamonds averaging 12 to 18 carats per 100 metric tons of kimberlite. The largest diamond recovered was a 5.51 carat gemstone. The site was determined to be sub-economic and was never mined commercially. I obtained this material in 2005 while supervising reclamation at the site. The Kelsey Lake Mine, a few miles north of the Sloan diatreme, produced diamonds between 1996 and 1998 and is the only commercial diamond mine to have operated in the United States. Both the Kelsey Lake Mine and the Sloan exploration openings have been backfilled and reclaimed, and the landowners do not allow visitors. This rough specimen comes from an exploration adit driven in the Sloan 2 diatreme in the 1990s. It weighs 214 grams, measures 2" x 3" x 2.5", and contains a red garnet xenolith along one edge. Kimberlite occurs in diatremes, vertical volcanic pipes formed by powerful, gas-driven eruptions. In addition to diamonds, Sloan kimberlite contains lower crustal and mantle indicator minerals including ilmenite, pyrope garnet, and chrome diopside, plus xenoliths of peridotite, dunite, eclogite, fossiliferous early Paleozoic limestone, and Precambrian rocks. References: Overview of the Sloan 1 & 2 Diamondiferous Kimberlite, Colorado-Wyoming State Line District, compiled by W. Dan Hausel, 1996 Industrial Minerals Forum Field Trip – Mineral Report MRS96-4, 1996. Diamonds and Mantle Source Rocks in the Wyoming Craton with a Discussion of Other U.S. Occurrences, by W. Dan Hausel, Wyoming Geological Survey Report of Investigations No. 53, 1998.
Availability
Sold Out
Own a genuine piece of Colorado's volcanic past with kimberlite sourced from the Sloan Diatreme, one of the most well-documented kimberlitic systems in the United States. Located in Larimer County, the Sloan pipe is part of the State Line Kimberlite District, a region historically explored for its diamond-bearing potential and rich mantle-derived mineral assemblages.
This kimberlite represents material brought rapidly to the surface from deep within the Earth's mantle, preserving a suite of classic indicator minerals used in diamond exploration.
Sloan kimberlite is especially valued for its accessibility, well-characterized mineralogy, and its role in advancing North American diamond exploration. Whether you are a collector, geology enthusiast, educator, or prospector, this material offers both scientific interest and display appeal.
Each specimen is natural, unprocessed kimberlite as recovered from the Sloan Diatreme area, providing an authentic glimpse into deep-earth processes and the mineral indicators that guide diamond exploration worldwide.
Classic kimberlite indicator minerals

Pyrope garnets (G9 and G10)
Chromium-rich garnets among the most important diamond indicator minerals. G10 garnets in particular are strongly associated with diamond stability fields at depth.
Magnesium ilmenite
A titanium-iron oxide often linked with diamondiferous kimberlites, useful for geochemical analysis and mantle source characterization.

Chrome diopside
A vibrant green clinopyroxene that forms under high-pressure mantle conditions, commonly recovered during kimberlite processing and an excellent visual indicator of mantle-derived origin.
