Definition
Troctolite is a mafic intrusive rock type. It consists essentially of major but variable amounts of olivine and calcic plagioclase along with minor pyroxene. It is an olivine-rich anorthosite, or a pyroxene-depleted relative of gabbro
Phonolite is an uncommon extrusive igneous rock volcanic rock of intermediate chemical composition between felsic and mafic
History
Origin
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Discoverer
Christian Leopold von Buch
Unknown
Etymology
From German Troklotit, from Greek trōktēs, a marine fish (taken to be trout)
From the Greek meaning sounding stone because of the metallic sound it produces if an unfractured plate is hit
Class
Igneous Rocks
Igneous Rocks
Sub-Class
Durable Rock, Hard Rock
Durable Rock, Medium Hardness Rock
Family
Group
Plutonic
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Other Categories
Coarse Grained Rock, Opaque Rock
Fine Grained Rock, Opaque Rock