Definition
Origin
Discoverer
Etymology
Class
Sub-Class
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Other Categories
Greywacke is defined as a dark coarse-grained sandstone rock which contains more than 15 per cent clay
From German Grauwacke, from grau grey + wacke
Fine Grained Rock, Opaque Rock
Hyaloclastite is an aggregate of fine, glassy debris formed by the sudden contact of hot, coherent magma and cold water or water-saturated sediment
Fine Grained Rock, Opaque Rock