2007-12-23 10:16:46 · 3 answers · asked by Anonymous in Science & Mathematics ➔ Earth Sciences & Geology
Greywacke (German grauwacke, signifying a grey, earthy rock) is a variety of sandstone generally characterized by its hardness, dark color, and poorly-sorted, angular grains of quartz, feldspar, and small rock fragments set in a compact, clay-fine matrix. It is a texturally-immature sedimentary rock generally found in Palaeozoic strata. The larger grains can be sand-to-gravel-sized, and matrix materials generally constitute more than 15% of the rock by volume.
2007-12-23 10:18:43 · answer #1 · answered by Emily Y 2 · 1⤊ 0⤋
Ya the wiki copied answer is about right I'd say. For me, a greywacke is an impure coarse-grained detrital sedimentary rock consisting in large part of rock fragments. Can't say that I have identified too many rocks in the field as greywacke rather than just as conglomerates, but that is likely more my error than anything.
2007-12-23 11:09:39 · answer #2 · answered by busterwasmycat 7 · 3⤊ 0⤋
Cite your sources Emily!
"Greywacke (German grauwacke, signifying a grey, earthy rock) is a variety of sandstone generally characterized by its hardness, dark color, and poorly-sorted, angular grains of quartz, feldspar, and small rock fragments set in a compact, clay-fine matrix. It is a texturally-immature sedimentary rock generally found in Palaeozoic strata. The larger grains can be sand-to-gravel-sized, and matrix materials generally constitute more than 15% of the rock by volume."
2007-12-23 11:08:14 · answer #3 · answered by Lady Geologist 7 · 1⤊ 0⤋