Definition
Rapakivi Granite is a hornblende-biotite Granite containing large rounded crystals of orthoclase which are mantled with oligoclase
Trachyte is a grey fine-grained volcanic rock which mainly consists of alkali feldspar
History
Origin
Finland, Europe
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Discoverer
Jakob Sederholm
Alexandre Brongniart and René Just Haüy
Etymology
From Finnish Rapakivi which stands for crumbly rock
From Greek trakhus rough’ or trakhutēs roughness
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Medium Hardness Rock
Family
Group
Plutonic
Volcanic
Other Categories
Coarse Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock