BETA

Deprecated function: Array and string offset access syntax with curly braces is deprecated in include_once() (line 20 of /var/www/preservation.nps.gov/html/buildingstone/includes/file.phar.inc).

Elberton Granite

Submitted by Ed FitzGerald on Mon, 2014-11-24 10:09
Trade Name Alias: 
Stone Type (Commercial): 
Description: 

The granite is a compact, fine-grained,even textured biotite granite, composed of bluish-gray feldspar, with somewhat pearly cleavage facies, clear colorless quartz and the ferro-magnesium mineral, biotite. The constitute grains of these minerals are closely and intricately interlocked.

ASTM data from North Carolina Granite Corporation.

Availability: 
Available
Physical Data
Absorption (%): 
0.26
Density (lb/cf): 
165.12
Flexural Strength, Dry (psi): 
1,724
Modulus of Rupture, Dry (psi): 
2,650
Compressive Strength, Dry (psi): 
39,960
Geology
Grain Shape: 
Very Angular
Angular
Grain Size: 
Coarse
Medium
Petrographic Description: 

Specimen 2014-060
This sample is a plutonic rock dominated by mostly anhedral feldspar and a lesser amount of quartz. The crystalline structure is generally coarse. Maximum crystal dimension is 3.5 mm (feldspar) and minimum is .05 mm (quartz). There is a fairly continuous gradation in grain sizes without a clear mode. Feldspar twinning is common and includes Carlsbad, tartan (microcline), and albite. Grain boundaries range from smooth curving to substantially consertal sutured. The latter is particularly common among quartz grain boundaries. Almost all quartz grains present wave extinction. Intergrowth textures include microperthitic involving multiple species of feldspar and granophyric with plagioclase intergrown with quartz. Accessory minerals include biotite, which is common at 5 to 10 percent of slide area. Muscovite is present at less than 5 percent of slide area; opaques also constitute less than 5 percent of slide area. There are only a few instances (basal) of what are likely an orthopyroxene. There are slight signs of insipient weathering of feldspars with many grains presenting a dusty look. What is likely sericite is present in small patches (~30 µm) on some feldspar grains.
MP 9/4/2014

Images

Click thumbnail for larger image.
Specimen ID
2014-060 Image of specimen in dry conditions. Finish: download image

Thin Sections

Click thumbnail for larger image.
Specimen ID Non-polarized Cross-polarized
2014-060 Specimen shown in non-polarized light.download image Specimen shown in cross-polarized light.download image

Quarry

NOTE: Quarry locations are approximate.

Bluestone Quarries
Elberton , Georgia
United States
34° 4' 29.4204" N, 82° 57' 22.176" W
Georgia US

Report an Issue