Pegmatite mineralogy of the Sawtooth Batholith, Idaho
The Sawtooth batholith is one of several anorogenic granite plutons in Central Idaho. These epizonal plutons, emplaced during the Challis volcanic-plutonic event, are for the most part associated with cauldera complexes of Tertiary age. Miarolitic cavities and small pegmatite dikes in the Sawtooth batholith contain a suite of uncommon minerals. The more common minerals of this suite are quartz (commonly smoky), microcline, albite, fluorite, hematite, topaz, and beryl (variety aquamarine). In addition a less common suite of Mn-rich minerals is found. These include helvite, spessartine garnet, zinnwaldite-masutomilite series micas, and a Mn-K-Li-rich member of the carpholite group. Of these rarer minerals the most interesting are the carpholite group member and the micas. The K occupies a crystallographic site which is normally vacant in carpholite group minerals and can have a maximum occupancy of 1. This mineral most likely represents a new species in the carpholite group. The zinnwaldite-masutomilite micas are rather low in Li and have Fe:Mn ratios ranging from about 2.2 to 0.5. These Li contents are typical of zinnwaldites from anorogenic granite pegmatites. However, all other reported occurrences of masutomilite have been richer in Li.
- Research Organization:
- Eastern Washington Univ., Cheney (USA)
- OSTI ID:
- 6595361
- Report Number(s):
- CONF-8510489-
- Journal Information:
- Geol. Soc. Am., Abstr. Programs; (United States), Vol. 17; Conference: 98. annual meeting of the Geological Society of America, Orlando, FL, USA, 28 Oct 1985
- Country of Publication:
- United States
- Language:
- English
Similar Records
NIOBIUM-ZIRCONIUM-THORIUM-URANIUM AND RARE-EARTH MINERALS FROM THE PEGMATITES OF SOUTH HARRIS, OUTER HEBRIDES
National Uranium Resource Evaluation, Portland Quadrangle: Maine and New Hampshire