Big Boulder Prospect

The Big Boulder Prospect is a mica mine located in Larimer county, Colorado at an elevation of 8,681 feet.

About the MRDS Data:

All mine locations were obtained from the USGS Mineral Resources Data System. The locations and other information in this database have not been verified for accuracy. It should be assumed that all mines are on private property.

Mine Info

Satelite View

MRDS mine locations are often very general, and in some cases are incorrect. Some mine remains have been covered or removed by modern industrial activity or by development of things like housing. The satellite view offers a quick glimpse as to whether the MRDS location corresponds to visible mine remains.

Site Name

Primary: Big Boulder Prospect

Commodity

Primary: Mica
Secondary: Uranium
Tertiary: Beryllium
Tertiary: Feldspar
Tertiary: Lithium

Location

State: Colorado
County: Larimer
District: Crystal Mountain (Storm Mountain) Pegmatite District

Land Status

Land ownership: State
Note: the land ownership field only identifies whether the area the mine is in is generally on public lands like Forest Service or BLM land, or if it is in an area that is generally private property. It does not definitively identify property status, nor does it indicate claim status or whether an area is open to prospecting. Always respect private property.

Holdings

Not available

Workings

Type: Surface/Underground

Ownership

Owner Name: State Of Colorado
Home Office: Colorado
Years: 1964 -

Owner Name: Helen Allphin
Home Office: Jamestown
Years: 1964 -

Production

Year: 1941
Material type: BE ACC
Description: Ap_Grade: ^0.10% U308

Deposit

Record Type: Site
Operation Category: Past Producer
Operation Type: Unknown
Year First Production: 1936
Year Last Production: 1961
Discovery Method: Ore-Mineral In Place
Years of Production:
Organization:
Significant: N
Deposit Size: S

Physiography

General Physiographic Area: Rocky Mountain System
Physiographic Province: Southern Rocky Mountains

Mineral Deposit Model

Not available

Orebody

Form: LENTICULAR

Form: LENTICULAR

Structure

Type: R
Description: Front Range Uplift

Type: L
Description: Thompson Canyon Fault, Mt Olympus Batholith, Ne-Trending Folds

Alterations

Not available

Rocks

Name: Tonalite
Role: Associated
Age Type: Associated Rock
Age Young: Neoproterozoic

Name: Tonalite
Role: Associated
Age Type: Host Rock
Age Young: Neoproterozoic

Analytical Data

Analytical Data: PROSPECT AVERAGES 0.5 % BERYL. WALL ZONE CONTAINS 0.75 % BERYL, LOWER INTERMEDIATE CONTAINS 0.37 % BERYL, UPPER INTERMEDIATE ZONE CONTAINS 0.07 % BERYL, AND CORE CONTAINS 0.06 % BERYL.

Materials

Ore: Beryl
Ore: Muscovite
Ore: Microcline
Gangue: Torbernite
Gangue: Garnet
Gangue: Apatite
Gangue: Tourmaline
Gangue: Spodumene

Comments

Comment (Deposit): ZONED PEGMATITE CONSISTS OF OUTER ZONE OF QUARTZ-ALBITE-MICROCLINE-MUSCOVITE PEGMATITE WITH ONE-INCH AVERAGE GRAIN SIZE AND ACCESSORY BERYL, TOURMALINE, AND APATITE. CORE CONSISTS OF MILKY QUARTZ AND GIANT MICROCLINE CRYSTALS WITH MINOR "ROTTEN" SPODUMENE AND SMALL AMOUNTS OF AUTUNITE AND GUMMITE. LENTICULAR BODY PROBABLY PINCHES OUT AT APPROX 125-FT DEPTH.

Comment (Reserve-Resource): HANLEY AND OTHERS, 1950

Comment (Location): ON DIVIDE BETWEEN SHEEP CREEK AND FISH CREEK SW OF BOILER HILL, 1.8 MILES SE OF CRYSTAL MOUNTAIN. ; INFO FROM LAND.ST :(1980)

Comment (Workings): FOUR SMALL OPEN CUTS; 10-FT SHAFT

References

Reference (Production): HANLEY AND OTHERS, 1950; NELSON-MOORE AND OTHERS, 1978; COLORADO DIV. MINES ANN. OPERATOR REPTS.

Reference (Deposit): HANLEY, J.B., AND OTHERS, 1950, PEGMATITE INVESTIGATIONS IN COLORADO, WYOMING, AND UTAH, 1942-1944: USGS PROF. PAPER 227, P. 92-93.

Reference (Deposit): MEEVES, H.C., AND OTHERS, 1966, RECONNAISSANCE OF BERYLLIUM-BEARING PEGMATITE DEPOSITS IN SIX WESTERN STATES: USBM IC-8298, P. 29.

Reference (Deposit): COLORADO DIV. MINES ANNUAL OPERATOR REPTS.

Reference (Deposit): NELSON-MOORE, J.L., AND OTHERS, 1978, RADIOACTIVE MINERAL OCCURRENCES OF COLORADO AND BIBLIOGRAPHY: CGS BULL. 40, P. 208.

Reference (Deposit): THURSTON, W.R., 1955, PEGMATITES OF THE CRYSTAL MOUNTAIN DISTRICT, LARIMER COUNTY, COLORADO: USGS BULL. 1011, 185 P., 13 PLS.

Colorado Mining Photos

Check out this collection of Colorado's best historic mining photos: Incredible Photos of Colorado Mining Scenes.