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).

Dakota Mahogany Whetstone

Submitted by Raven Mueller on Wed, 2014-07-02 16:46
Stone Type (Commercial): 
Availability: 
Available
Physical Data
Munsell Color(s): 
Absorption (%): 
0.11
Flexural Strength, Dry (psi): 
1,598
Modulus of Rupture, Dry (psi): 
2,820
Compressive Strength, Dry (psi): 
22,500
Abrasion Resistance: 
57.08
Geology
Stone Type (Lithologic): 
Chronostratigraphy: 
Rock Unit: 
Grain Shape: 
Angular
Grain Size: 
Coarse
Petrographic Description: 

Specimen: 2013-001

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 15 mm (feldspar) and minimum is .1 mm (quartz). Modal grain size is from 4 to 1.5 mm. There are a variety of feldspar twinning patterns including tartan (microcline), Carlsbad, and albite. Grain boundaries range from smooth curving to substantially consertal sutured. The latter is particularly common among quartz and feldspar grain boundaries. Intergrowth textures include microperthitic involving multiple species of feldspar and granophyric with plagioclase intergrown with quartz. Accessory minerals include biotite, which is common at about 10 percent of slide area, and muscovite, which is extremely rare. No amphiboles or pyroxenes are visible in this slide. Opaques are also relatively rare and comprise less than 5 percent of slide area. 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 (~10 µm) on some feldspar grains. Rarely, grain boundaries and cracks in grains have begun to fill with reddish brown clay material (>20 µm in width).
7/7/2015 MP

Images

Click thumbnail for larger image.
Specimen ID
2013-001 Image of specimen in dry conditions. Finish: Polisheddownload image

Thin Sections

Click thumbnail for larger image.
Specimen ID Non-polarized Cross-polarized
2013-001 Specimen shown in non-polarized light.download image Specimen shown in cross-polarized light.download image

Quarry

NOTE: Quarry locations are approximate.

Whetstone Quarry
48391 150th St.
Milbank , South Dakota
United States
45° 12' 35.9064" N, 96° 30' 52.92" W
South Dakota US

Report an Issue