Definition
Greywacke is defined as a dark coarse-grained sandstone rock which contains more than 15 per cent clay
Picrite is a variety of high-magnesium olivine basalt that is very rich in the mineral olivine
History
Origin
-
Hawaii Islands
Discoverer
Unknown
Unknown
Etymology
From German Grauwacke, from grau grey + wacke
From Greek pikros bitter + -ite, 19th century
Class
Sedimentary Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Hard Rock
Family
Group
-
Volcanic
Other Categories
Fine Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock