Rhyolite
Hand Sample: Porphyritic rhyolite with medium-grained potassium feldspar and plagioclase feldspar phenocrysts in a dark red-brown matrix. Weathers with an orangish tinge.
Thin Section: Coarse-grained subhedral plagioclase feldspar phenocrysts in matrix. Opaques present.
1/20/1969
Western Minerals Inc.
SFM-31
Stegall Rhyolite (Middlebrook group)
Hand Sample: Porphyritic rhyolite with medium-grained Potassium feldspar phenocrysts in a brown-red groundmass. Weathers to yellow-brown.
Thin Section: Medium-grained subhedral quartz and plagioclase phenocrysts in matrix.
1/20/1969
Western Minerals, Inc.
SFM-30
Wills Granite (Musco group)
Hand Sample: Fine-grained phaneritic granite. Mineralogy includes potassium feldspar, quartz and a black mineral. Weathers to light orange.
Thin Section, XPL: 60% plagioclase, 30% quartz, 10% very-fine-grained biotite
1/20/1969
Western Minerals, Inc.
SFM-29
Silvermine Granite
Hand Sample: Holocrystalline, fine-to-medium-grained granite. Mineralogy includes potassium feldspar and quartz. One corner of rock has a mass of dark grey-brown groundmass with inclusions of plagioclase laths and anhedral grey-green crystals. Weathers with a pinkish-orange.
Thin Section: 40% fine-grained well-weathered quartz, 40% fine-grained plagioclase feldspar, 10% biotite, 10% opaques
1/20/1969
Western Minerals, Inc.
SFM-28
Mudlick Latite
Hand Sample: Porphyritic latite with medium-to-coarse-grained subhedral plagioclase phenocrysts in a brown-black groundmass. Thin black veins present with green margin of contact on either side.
Thin Section, XPL: Medium-grained subhedral phenocrysts of plagioclase feldspar, quartz, and microcline feldspar in a matrix that appears to be made from the same minerals. Very fine vein of greenish minerals runs through sample.
1/20/1969
Western Minerals, Inc.
SFM-27
Magee Granite
Hand Sample: Holocrystalline medium-grained phaneritic granite with crystals including potassium feldspar and smokey quartz.
Thin Section: Well-weathered subhedral grains, 60% medium-grained potassium feldspar 40% medium grained quartz
1/20/1969
Western Minerals, Inc.
SFM-26
Stono Granite
Hand Sample: Holocrystalline, fine-grained phaneritic granite with crystals of potassium feldspar and smoky quartz. Weathers to orange-brown and light-gray.
Thin Section: Very weathered coarse-grained phenocrysts of quartz, alkali feldspar, and plagioclase feldspar. Smaller crystals of the same minerals and biotite surround the phenocrysts.
1/20/1969
Western Minerals, Inc.
SFM-25
Porphyritic Granite Dike
Hand Sample: Phaneritic granite with coarse-grained phenocrysts of smokey quartz and generally smaller crystals including potassium feldspar. Weathers to orange on one side and some light-gray material on the other.
Thin Section: 25% coarse-grained quartz phenocrysts in a matrix of 40% fine-grained rectangular plagioclase laths, 30% fine-grained alkali feldspar, and 30% fine-grained quartz.
1/20/1969
Western Minerals, Inc.
SFM-24
Graniteville Granite
Hand Sample: Holocrystalline, medium-grained phaneritic granite with smoky quartz, potassium feldspar, and biotite
Thin Section, XPL: 40% medium-to-fine grained subhedral quartz, 30% fine-grained plagioclase, 30% medium-grained euhedral alkali feldspar
1/20/1969
Western Minerals, Inc.
SFM-23
Hogan Rhyolite (VanEast group)
Hand Sample: Porphyritic fine-grained light-pink and black phenocrysts in a reddish-purple-brown matrix. Hospitable to grey-brown lichen.
Thin Section: Primarily matrix with very-fine grains of well-weatherd opaques and quartz with a high purple and blue biofringence
1/20/1969
Western Minerals, Inc.
SFM-22
Royal Gorge Rhyolite
Hand Sample: Porphyritic medium-grained phenocrysts of potassium feldspar in a dark purple-red groundmass. Weathers to white and orange-brown.
Thin Section: Primarily matrix with some very-fine anhedral grains of a mineral with high blue birefringence. Some fine-grained anhedral well-weathered and fractured quartz grains. Opaques present.
1/20/1969
Western Minerals Inc.
SFM-21
Devonite (diabase-porphyry)
Hand Sample: Porphyritic diabase with coarse to very coarse grained subhedral pink-green plagioclase laths approximately 3cm in length set in a gray-black matrix. Inclusions of matrix present within plagioclase laths. Weathers to orange-brown.
Thin Section: Plagioclase laths fractured and rimmed with chlorite. Matrix includes 55% fine-grained interlocking euhedral plagioclase laths,10% opaques, among other mixed minerals.
1/20/1969
Western Minerals, Inc
SFM-20
Albitite
Hand Sample: Aphanitic, grayish-white with some patches of fine-grained grey crystals. Weathers to medium yellow-brown.
Thin Section: 90% medium-grained well-weathered subhedral microcline, 10% plagioclase feldspar.
1/20/1969
Western Minerals, Inc.
SFM-19
Marlow Mountain Rhyolite
Hand Sample: Phaneritic rhyolite. 10% fine-grained phenocrysts of sanidine and quartz and 90% dark-brownish-red groundmass. Weathers to brown-orange.
Thin Section: Very weathered matrix with a few fine-grained anhedral crystals of feldspar and quartz
1/20/1969
Western Minerals, Inc.
SFM-18
French Mills Rhyolite
Hand Sample: Phaneritic rhyolite with fine-grained phenocrysts of quarts, feldspar and hornblende in a brownish-red groundmass. Weathers to orange-brown.
Thin Section, XPL: 50% medium-to-fine grained subhedral well-weathered plagioclase crystals, some rimmed in opaques. 50% matrix.
1/20/1969
Western Minerals, Inc.
SFM-17
Altered Basalt Flow
Hand Sample: Aphanitic grey-black color. Weathers to yellow-tan and orange. Small vesicles present.
Thin Section: Primarily matrix of opaques and some mica. Clusters of very-fine grained olivine and feldspar crystals present
1/20/1969
Western Minerals, Inc.
SFM-16
Ketcherside Tuff
Hand Sample: Aphanitic, pyroclastic grey-black tuff. Conchoidal fracture pattern from a strike-point on one edge. Weathers to yellow-brown.
Thin Section, XPL: 40% well weathered very-fine quartz, feldspar, and opaques with blurred edges in 60% matrix.
1/20/1969
Western Minerals, Inc.
SFM-15
Diorite (coarse-grained)
Hand Sample: Porphyritic (or coarse-grained phaneritic) diorite with coarse-grained white plagioclase laths up to 1cm and some black mineral. Weathering to rust-orange color.
Thin Section: 60% medium-grained interlocking rectangular plagioclase laths. Well-weathered smaller grains of quartz, biotite, and opaques fill in the spaces between laths.
1/20/1969
Western Minerals, Inc.
SFM-14
Brown Mountain intrusive Rhyolite
Hand Sample: Porphyritic orange-pink rhyolite. Dominantly potassium feldspar with some black crystals. Weathers to brown-black and yellow-brown.
Thin Section, XPL: Fine-grained, well-weathered quartz and alkaline feldspar interspersed with fine-grained rectangular inclusions of mixed material. Opaques present.
1/20/1969
Western Minerals, Inc.
SFM-13
Stouts Creek Rhyolite (VanEast group)
Hand Sample: Hypocrystalline, porphyritic rhyolite. 20% subhedral to anhedral biotite, quartz, and microcline (sanidine) phenocrysts. 80% grey-brown groundmass. Massive.
Thin Section, XPL: 50% subhedral, medium and fine-grained quartz and plagioclase crystals in 50% matrix that contains opaques and quartz among other minerals. Hexagonal inclusion of very-fine-grained, subhedral, well-weathered grains of quartz, biotite, and opaques.
1/20/1969
Western Minerals, Inc
SFM-12