Sierra Rose

Submitted by Ed FitzGerald on Tue, 2015-01-13 16:28
Stone Type (Commercial): 
Physical Data
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Compressive Strength, Dry (psi): 
Stone Type (Lithologic): 
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Petrographic Description: 

Specimen: 2014-086
This sample is a plutonic rock dominated by mostly anhedral phaneritic feldspar and a lesser amount of quartz. The crystalline structure is coarse. Maximum crystal dimension is 6.4 mm (feldspar). There is not a clear mode to crystal size, but most are between 1 and 4 mm. Carlsbad is the most prevalent twinning pattern but polysynthetic twins are also common. Grain boundaries range from smooth curving to consertal sutured. Stress induced wave extinction in quartz is common and some grain nucleation has clearly occurred. Microperthitic intergrowth textures are extremely common in feldspars. Accessory minerals include biotite at about 10 percent of slide area. A green-brown amphibole, likely hornblende, is also relatively common at around 5 to 10 percent of slide area. Opaques are present in trace amounts. There is one crystal of a mafic mineral that has completely transformed to alteration minerals, growing in volume in the process and shattering the surrounding quartz grains. There are slight signs of incipient weathering of feldspars with many grains presenting a dusty look. Sericitization is minimal. There are small cracks filled with iron oxides and hydroxides and clay minerals about 8 µm in width.


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Specimen ID
2014-086 Image of specimen in dry conditions. Finish: download image

Thin Sections

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Specimen ID Non-polarized Cross-polarized
2014-086 Specimen shown in non-polarized image Specimen shown in cross-polarized image


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