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Dumortierite Pegmatite Locality (MRDS - 10019821), Ruby Range, Madison Co., Montana, USA

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A granite pegmatite exposure extending over 650 meters long and up to 20 meters wide. It is noteworthy that Graham and Robsertson (1951) found several additional boron silicates that they could not identify. Two colors (blue and green) of dumortierite were "identified", but the rare minerals seemed to be associated with the blue dumortierite preferentially. The USBM co-ordinates may be in error as they seem to put the pegmatite on the wrong fork of the souther tributary. The locality does straddle a southern tributary of Spring Creek and is located across the boundary of Sections 3 and 4 of Township 7 South, Range 6 West. The co-ordinates were chosen fropm an estimate of the position shown in Graham and Robertson (1951) and the Christiansen Ranch Quadrangle map of Spring Creek.

Deposit:: CONSV. DIV. COMP. DATE, 05-27-1963
Commodities (Major) - Aluminum
Development Status: Occurrence
Host Rock Unit: Pre Belt
Host Rock: Gneiss, Schist

Mineral List

7 entries listed. 5 valid minerals.

The above list contains all mineral locality references listed on This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.


GRAHAM, Charles AND ROBERTSON, Forbes (1951) A New Dumortierite Locality from Montana, American Mineralogist, V. 36, NO. 11-12, p. 916-917.

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