Definition
Greywacke is defined as a dark coarse-grained sandstone rock which contains more than 15 per cent clay
Lignite is a soft brownish coal which shows traces of plants and is intermediate between bituminous coal and peat
History
Origin
-
France
Discoverer
Unknown
Unknown
Etymology
From German Grauwacke, from grau grey + wacke
From French, Latin lignum wood + -ite1
Class
Sedimentary Rocks
Sedimentary Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Soft Rock
Family
Group
-
-
Other Categories
Fine Grained Rock, Opaque Rock
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock