Our website is made possible by displaying online advertisements to our visitors.
Please consider supporting us by disabling your ad blocker.

Responsive image

Greywacke

Photomicrographs of feldspathic (L) and lithic (R) greywacke. The top images are in plane-polarized light; the bottom images are in cross-polarized light. Cements fill the pore spaces.
Closeup of Pharaoh Menkaure's greywacke statue, 25th century BCE, from the Egyptian Museum in Cairo

Greywacke or graywacke (German grauwacke, signifying a grey, earthy rock) is a variety of sandstone generally characterized by its hardness (6–7 on Mohs scale), dark color, and poorly sorted angular grains of quartz, feldspar, and small rock fragments or sand-size lithic fragments set in a compact, clay-fine matrix. It is a texturally immature sedimentary rock generally found in Paleozoic strata. The larger grains can be sand- to gravel-sized, and matrix materials generally constitute more than 15% of the rock by volume.


Previous Page Next Page






جرواق Arabic Граўвака BE Grauvaca Catalan Droba Czech Grauwacke German Graŭvako EO Grauvaca Spanish Graubaka EU Grauwacke French Gréabhaca GA

Responsive image

Responsive image