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Biotite from
Cotopaxi Mine (Cotopaxi lode; Gumaer Mine; Fannie lode; Fannie Mill), Mine Gulch, Cotopaxi, Cotopaxi Mining District, Fremont County, Colorado, USA


Locality type:Mine
Classification
Species:'Biotite' (not an IMA approved species)
Formula:K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Confirmation
Validity:Believed Valid
Data
Mineral Data:Click here to view Biotite data
Locality Data:Click here to view Cotopaxi Mine (Cotopaxi lode; Gumaer Mine; Fannie lode; Fannie Mill), Mine Gulch, Cotopaxi, Cotopaxi Mining District, Fremont County, Colorado, USA
Data Identifiers
Mindat Occurrence Record ID:149191
Long-form Identifier:1:3:149191:3
GUID (UUID V4):0
Nearest other occurrences of Biotite
0.3km (0.2 miles) ⓘCotopaxi Mining District, Fremont County, Colorado, USA
3.8km (2.4 miles) ⓘMcCoy prospects, Cotopaxi Pegmatite area, Cotopaxi, Cotopaxi Mining District, Fremont County, Colorado, USA
4.9km (3.0 miles) ⓘCotopaxi Feldspar Mine (Cotopaxi Feldspar prospect; Henry pegmatite), Cotopaxi Pegmatite area, Cotopaxi, Cotopaxi Mining District, Fremont County, Colorado, USA
5.9km (3.7 miles) ⓘColorado Feldspar Pegmatite, Cotopaxi Mining District, Fremont County, Colorado, USA
10.4km (6.4 miles) ⓘKnob Hill prospect (Knob Hill pegmatite), Howard, Cotopaxi Mining District, Fremont County, Colorado, USA
11.9km (7.4 miles) ⓘSchaaf prospect, Cotopaxi Pegmatite area, Cotopaxi, Cotopaxi Mining District, Fremont County, Colorado, USA
12.2km (7.6 miles) ⓘPine Ridge pegmatite, Cotopaxi Pegmatite area, Cotopaxi, Cotopaxi Mining District, Fremont County, Colorado, USA
13.2km (8.2 miles) ⓘHighway 50 roadcut, Texas Creek Area, Fremont County, Colorado, USA
13.6km (8.4 miles) ⓘHoward prospects, Howard, Cotopaxi Mining District, Fremont County, Colorado, USA
14.1km (8.7 miles) ⓘDevil's Hole Mine, Fremont County, Colorado, USA
References
Am Min 50:1179-1212
USGS Prof Paper 223
Pearl, Richard M. (1958) Colorado Gem Trails and Mineral Guide (1st ed.) Sage Books, Denver, CO.
(2005). The Canadian Mineralogist 43, 601-622.
Spry, Paul G.; McFadden, Scott; Teale, Graham S.; Alers, Brian; Shallow, John M.; Glenn, Justin M. (2022) Nodular sillimanite rocks as field indicators to metamorphosed massive sulfide deposits. Ore Geology Reviews, 141. 104632 doi:10.1016/j.oregeorev.2021.104632
 
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