Mine detail: Black Rock Group

Previously called 'Black Magic Prospects'

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Location

Lat / long:

33.0776, -109.29343

Resource(M)

Primary:	Manganese
Ore:	Psilomelane, Pyrolusite
Orebody form:	IRREGULAR
Discovery year:	1906

Production

Operation type:	Unknown
Production size:	Small
Development status:	Producer
First production started:	1951

Geology

Host rock:	Longfellow Limestone
Host type:	Limestone,Chert
Associated rock:	Precambrian Granite-Granodiorite Complex
Associated type:	Granite
Structure:	Ne Trending Large Fault Between Limestone And Precambrian Granite That Comprises Massivebluffs Overlooking The San Francisco River, Upper Contact Of Chert And Limestone Is Very Irregular; Most Ore Exposures Are Located On The Canyon Walls 20 To 40 Ft Above The Bed Of The Gulch
Tectonic:	Deeply Sunken Limestone Fault Blocks East Of Copper King Massif; Vertical Throw Of About 3000 Ft
Alteration processes:	Manganese Ore Occurs As Replacement Of Limestone Bordering Large Fault; Replacement Of Crushed Chert Particles In Brecciated Areas

References

MRDS	M800416
DEP	10109875
Reference	{Deposit:: USBM IC 7990, P. 101-102.}{Deposit:: USBM FILES, BLACK ROCK GROUP.}{Deposit:: ABGMT CLIPPINGS FILE, BLACK ROCK MINE.}{Deposit:: USGS PP 43, SAN FRANCISCO RIVER GEOLOGY COMMENTS.}{Deposit:: BENNETT, K.C., 1975, GEOLOGY AND ORIGIN OF THE BRECCIAS IN THE MORENI-METCALF DISTRICT, GREENLEE COUNTY, ARIZONA: M.S. THESIS, UNIVERSITY OF ARIZONA, 153 P.}{Deposit:: ADMR FILE DATA, BLACK ROCK MINES.}{Production:: USBM I.C. 7990, P. 101.}
Reporter	Calder, Susan R.