Where is troctolite found?
Troctolite is found in some layered intrusions such as in the Archean Windimurra intrusion of Western Australia, the Voisey’s Bay nickel-copper-cobalt magmatic sulfide deposit of northern Labrador, the Stillwater igneous complex of Montana, the Duluth Complex of the North American Midcontinent Rift, and the Tertiary …
What is the composition of troctolite?
troctolite, coarse-grained, intrusive igneous rock that is composed almost entirely of olivine (often iron-rich) and plagioclase feldspar (labradorite or bytownite).
How is troctolite formed?
The genesis of troctolite is also strongly tied to gabbro. These two rocks usually occur together in the same magma intrusion because troctolite can not form directly as magma crystallizes. There is no way how magma can crystallize into olivine and plagioclase without pyroxene.
What is Picrite rock?
picrite, intrusive igneous rock of ultramafic (very silica-poor) composition that is composed largely of olivine and augite and is somewhat similar to peridotite. Picrites are dark, heavy rocks and contain a small but variable amount of plagioclase feldspar; hornblende and biotite may also be present.
Is monzonite a rock?
monzonite, intrusive igneous rock that contains abundant and approximately equal amounts of plagioclase and potash feldspar; it also contains subordinate amounts of biotite and hornblende, and sometimes minor quantities of orthopyroxene.
Is gabbro a granite?
Granite is a coarse-grained igneous rock with average grain size ranging from 1 to 25 millimeters. Gabbro is generally coarse grained, with crystals in the size range of 1 mm or greater.
What is the crystal size of Gabbro?
1 mm
Gabbro is generally coarse-grained, with crystals in the size range of 1 mm or larger.
What is the difference between quartz monzonite and granite?
Granite contains predominantly an alkalic feldspar (generally microcline or orthoclase), whereas quartz monzonite contains roughly equal parts of alkalic feldspar and plagioclase. Chemically, therefore, granite contains more of the alkali metals sodium and potassium and less calcium than quartz monzonite does.
How is a troctolite different from a gabbro?
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. However, unlike gabbro, no troctolite corresponds in composition to a partial melt of peridotite.
What kind of crystals are in a troctolite?
Troctolite, from Greek “troctos” and “lithos” = trout rock due to the look “spotted”, due to the presence of olivine crystals, consists essentially of major but variable amounts of olivine and calcic plagioclase along with variable minor pyroxene. It is an olivine-rich, pyroxene-depleted relative of gabbro.
What can you do with a gabbro rock?
Gabbro can be polished to a bright black glow. Bright polished gabbro cemetery signs are used in kitchen stalls, floor tiles, facade stone and other size stone products. It is a highly desirable rock based on weather and wear.
What makes a gabbro rock a diorite?
It is a small amount of olivine and amphibole. Plagioclase is sodium-calcium feldspar. Gabrobro contains more calcium than sodium. If there is more sodium in the plagioclase, then the rock type is called diorite. Gabbro is greenish and dark.