Definition
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Tachylite is a vitreous form of basaltic volcanic glass. This glass is formed naturally by the rapid cooling of molten basalt
From German Tachylite, from tachy- + Greek lutos soluble, melting
Durable Rock, Medium Hardness Rock
Coarse Grained Rock, Fine Grained Rock, Medium Grained Rock, Opaque Rock
Coquina is a sedimentary rock that is composed either wholly or almost entirely of the transported, abraded, and mechanically-sorted fragments of the shells of molluscs, trilobites, brachiopods, or other invertebrates
From Concha (Latin)+ Coquina(Spanish) +conch(English)= Couquina (mid 19th century)
Coarse Grained Rock, Opaque Rock