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Little Gem Mine, Boulder Batholith, Jefferson Co., Montana, USAi
Regional Level Types
Little Gem MineMine
Boulder BatholithBatholith
Jefferson Co.County
MontanaState
USACountry

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Latitude & Longitude (WGS84):
46° North , 112° West (est.)
Estimate based on other nearby localities or region boundaries.
Margin of Error:
~22km
Locality type:


The Little Gem Mine was discovered prior to 1918. Claim papers from that year reference an "existing pit". Claim was re-filed by Jerry Gray in 1958. Gray worked the surface sporadically for 30+ years, brought in heavy equipment to build road access in the early 1990's. His goal was to create a secure working environment protected from trespassers. He tunneled about 100 feet through solid granite to reach the core, where it appears he hit a large pocket. A narrow raise follows an aplite zone upwards and east; the raise opened a series of pockets that he extended into a drift, which runs parallel to the core.
The present owner purchased the claim after Gray's death. Since 2010 it has been worked from the surface, utilizing blasting and an excavator. In 2013 the old drift in aplite was de-roofed and its access buried. Current work has exposed many pockets containing fine amethyst scepters and jacare' texture amethyst.

Regions containing this locality

North America PlateTectonic Plate
Rocky Mountains, North AmericaMountain Range

Select Mineral List Type

Standard Detailed Strunz Dana Chemical Elements

Mineral List


9 valid minerals.

Detailed Mineral List:

Anatase
Formula: TiO2
Reference: Chris Tucker
Brookite
Formula: TiO2
Reference: Chris Tucker
Epidote
Formula: {Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH)
Reference: The Lapidary Journal, May 1985
Goethite
Formula: α-Fe3+O(OH)
Reference: van Laer, in preparation
Malachite
Formula: Cu2(CO3)(OH)2
Reference: Chris Tucker
Microcline
Formula: K(AlSi3O8)
Reference: The Lapidary Journal, May 1985
Quartz
Formula: SiO2
Reference: NBMG Spec. Pub. 31 Minerals of Nevada
Quartz var: Amethyst
Formula: SiO2
Reference: NBMG Spec. Pub. 31 Minerals of Nevada
Quartz var: Sceptre Quartz
Formula: SiO2
Reference: JR Montgomery Collection
Quartz var: Smoky Quartz
Formula: SiO2
Reference: NBMG Spec. Pub. 31 Minerals of Nevada
Schorl
Formula: Na(Fe2+3)Al6(Si6O18)(BO3)3(OH)3(OH)
Reference: Rocks and Minerals Vol. 87, no 3 May/June
Titanite
Formula: CaTi(SiO4)O
Reference: Rocks and Minerals Vol. 87, no 3 May/June

List of minerals arranged by Strunz 10th Edition classification

Group 4 - Oxides and Hydroxides
Anatase4.DD.05TiO2
Brookite4.DD.10TiO2
Goethite4.00.α-Fe3+O(OH)
Quartz4.DA.05SiO2
var: Amethyst4.DA.05SiO2
var: Sceptre Quartz4.DA.05SiO2
var: Smoky Quartz4.DA.05SiO2
Group 5 - Nitrates and Carbonates
Malachite5.BA.10Cu2(CO3)(OH)2
Group 9 - Silicates
Epidote9.BG.05a{Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH)
Microcline9.FA.30K(AlSi3O8)
Schorl9.CK.05Na(Fe2+3)Al6(Si6O18)(BO3)3(OH)3(OH)
Titanite9.AG.15CaTi(SiO4)O

List of minerals arranged by Dana 8th Edition classification

Group 4 - SIMPLE OXIDES
AX2
Anatase4.4.4.1TiO2
Brookite4.4.5.1TiO2
Group 6 - HYDROXIDES AND OXIDES CONTAINING HYDROXYL
XO(OH)
Goethite6.1.1.2α-Fe3+O(OH)
Group 16a - ANHYDROUS CARBONATES CONTAINING HYDROXYL OR HALOGEN
Malachite16a.3.1.1Cu2(CO3)(OH)2
Group 52 - NESOSILICATES Insular SiO4 Groups and O,OH,F,H2O
Insular SiO4 Groups and O, OH, F, and H2O with cations in [6] and/or >[6] coordination
Titanite52.4.3.1CaTi(SiO4)O
Group 58 - SOROSILICATES Insular, Mixed, Single, and Larger Tetrahedral Groups
Insular, Mixed, Single, and Larger Tetrahedral Groups with cations in [6] and higher coordination; single and double groups (n = 1, 2)
Epidote58.2.1a.7{Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH)
Group 61 - CYCLOSILICATES Six-Membered Rings
Six-Membered Rings with borate groups
Schorl61.3.1.10Na(Fe2+3)Al6(Si6O18)(BO3)3(OH)3(OH)
Group 75 - TECTOSILICATES Si Tetrahedral Frameworks
Si Tetrahedral Frameworks - SiO2 with [4] coordinated Si
Quartz75.1.3.1SiO2
Group 76 - TECTOSILICATES Al-Si Framework
Al-Si Framework with Al-Si frameworks
Microcline76.1.1.5K(AlSi3O8)
Unclassified Minerals, Mixtures, etc.
Quartz
var: Amethyst
-SiO2
var: Sceptre Quartz-SiO2
var: Smoky Quartz-SiO2

List of minerals for each chemical element

HHydrogen
H Epidote{Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH)
H MalachiteCu2(CO3)(OH)2
H Goethiteα-Fe3+O(OH)
H SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
BBoron
B SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
CCarbon
C MalachiteCu2(CO3)(OH)2
OOxygen
O Quartz (var: Smoky Quartz)SiO2
O Quartz (var: Amethyst)SiO2
O MicroclineK(AlSi3O8)
O Epidote{Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH)
O AnataseTiO2
O BrookiteTiO2
O MalachiteCu2(CO3)(OH)2
O Goethiteα-Fe3+O(OH)
O SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
O TitaniteCaTi(SiO4)O
O QuartzSiO2
O Quartz (var: Sceptre Quartz)SiO2
NaSodium
Na SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
AlAluminium
Al MicroclineK(AlSi3O8)
Al Epidote{Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH)
Al SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
SiSilicon
Si Quartz (var: Smoky Quartz)SiO2
Si Quartz (var: Amethyst)SiO2
Si MicroclineK(AlSi3O8)
Si Epidote{Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH)
Si SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
Si TitaniteCaTi(SiO4)O
Si QuartzSiO2
Si Quartz (var: Sceptre Quartz)SiO2
KPotassium
K MicroclineK(AlSi3O8)
CaCalcium
Ca Epidote{Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH)
Ca TitaniteCaTi(SiO4)O
TiTitanium
Ti AnataseTiO2
Ti BrookiteTiO2
Ti TitaniteCaTi(SiO4)O
FeIron
Fe Epidote{Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH)
Fe Goethiteα-Fe3+O(OH)
Fe SchorlNa(Fe32+)Al6(Si6O18)(BO3)3(OH)3(OH)
CuCopper
Cu MalachiteCu2(CO3)(OH)2

References

Sort by

Year (asc) Year (desc) Author (A-Z) Author (Z-A)
Lasmanis, R. (1972) Butte Pegmatite Belt, Silver Bow and Jefferson counties, Montana. Rocks & Minerals: 47(3):160-164.
The Lapidary Journal, May 1985.
Hage, pers. comm (2011).
Rocks and Minerals (2012): 87(3).
Hage, R., Menzies, M.A. (2018) The Little Gem amethyst mine, Jefferson County, Montana. Rocks and Minerals: 93(6):498-516.

Mindat Articles

Big Amethyst at Little Gem by Bob Jackson



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