Bigger Mica Mine

The Bigger Mica Mine is a feldspar, mica, and beryllium mine located in Jefferson county, Colorado at an elevation of 7,300 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: Bigger Mica Mine
Secondary: Sweitzer Lode

Commodity

Primary: Feldspar
Primary: Mica
Primary: Beryllium
Tertiary: Uranium
Tertiary: REE
Tertiary: Tantalum
Tertiary: Bismuth
Tertiary: Niobium (Columbium)
Tertiary: Tin

Location

State: Colorado
County: Jefferson
District: Clear Creek Pegmatite Province

Land Status

Land ownership: Private
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

Not available

Production

Not available

Deposit

Record Type: Site
Operation Category: Past Producer
Operation Type: Unknown
Year First Production: 1884
Year Last Production: 1935
Discovery Year: 1884
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: TABULAR

Structure

Type: R
Description: Front Range Uplift, Denver Basin

Type: L
Description: Floyd Hill Fault Zone

Alterations

Not available

Rocks

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

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

Analytical Data

Analytical Data: HAND-COBBED BERYL CONTAINED 12.1% BEO

Materials

Ore: Monazite
Ore: Cassiterite
Ore: Bismutite
Ore: Microcline
Ore: Muscovite
Ore: Bismuthinite
Ore: Columbite
Ore: Beryl
Gangue: Albite
Gangue: Quartz
Gangue: Tourmaline
Unknown: Uraninite

Comments

Comment (Location): WEST OF SWITZERS GULCH 0.6 MILES SE OF FENDERS ; INFO FROM LAND.ST :(1975)

Comment (Development): SUPPOSEDLY PROSPECTED AND FIRST OPENED FOR SN. MINED FOR MICA IN 1888-1890, THEN FOR FELDSPAR IN 1937. PRODUCTION TO 1937 HAS BEEN AT LEAST 3000 TONS FELDSPAR, 1000 TONS SCRAP MICA, 18.9 TONS BERYL.

Comment (Deposit): ZONED PEGMATITE TRENDS GENERALLY N 40 W, 75 SW, AND IS CUT BY TWO FAULTS: NORTH FAULT TRENDS N46 E, 30 NW; EAST FAULT TRENDS N85 E, 60 NW, WALL ZONE IS 6 TO 11 FT THICK AND CONTAINS MEDIUM-GRAINED QUARTZ-MICROCLINE-BIOTITE-ALBITE PEGMATITE. AVE. 2-FT-THICK INTERMEDIATE ZONE CONTAINS QUARTZ-ALBITE-MUSCOVITE PEGMATITE. CORE CONTAINS MICROCLINE-QUARTZ PEGMATITE IN VERY COARSE CRYSTALS. INTERMEDIATE ZONE CONTAINS BERYL, BI MINERALS, TOURMALINE, CB, MONAZITE; U REPORTED BUT NOT FOUND BY HANLEY AND OTHERS.

Comment (Workings): IRREGULAR OPEN CUT, 50-FT ADIT CONNECTING AT DEPTH WITH 80-FT SHAFT

Comment (Deposit): DUPLICATE D001820 DELETED ; INFO.SRC : 1 PUB LIT

References

Reference (Deposit): BRYANT, BRUCE, AND OTHERS, 1973, GEOLOGIC MAP OF THE INDIAN HILLS QUADRANGLE, JEFFERSON COUNTY, COLORADO: USGS MAP GQ-1073

Reference (Deposit): HANLEY, J.B., AND OTHERS, 1950, PEGMATITE INVESTIGATIONS IN COLORADO, WYOMING, AND UTAH, 1942-44: USGS PROF. PAPER 227, P. 82-84

Reference (Deposit): MEEVES, H.C., AND OTHERS, 1966, RECONNAISSANCE OF BERYLLIUM-BEARING PEGMATITE DEPOSITS IN SIX WESTERN STATES: USBM IC-8298, P. 27.

Colorado Mining Photos

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