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