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Geochemistry Reference Libraries

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Diorite
2005-05-26 11:01:52

Diorite is a grey to dark grey intermediate intrusive igneous rock composed principally of plagioclase feldspar (typically andesine), hornblende, and/or pyroxene. Varieties deficient in hornblende and other dark minerals are called leucodiorite. It is often described as "salt and pepper" when composed largely of light-colored minerals randomly interspersed with dark minerals. When olivine and...

Gabbro
2005-05-26 11:00:22

Gabbro is a dark, coarse-grained, intrusive igneous rock chemically equivalent to basalt. It is a plutonic rock, formed when molten magma is trapped beneath the Earth's surface and cools slowly into a hard, coarsely crystalline mass. It is dense, greenish or dark-colored and contains varied percentages of plagioclase feldspar, pyroxene, amphibole, and olivine (called olivine gabbro when olivine...

Syenite
2005-05-25 11:55:01

Syenite is a coarse-grained intrusive igneous rock of the same general composition as granite but with the quartz either absent or present in relatively small amounts. The feldspars are alkaline in character and the dark mineral is usually hornblende. Soda-lime feldspars may be present in small quantities. The term syenite was originally applied to hornblende granite like that of Syene in...

Word of the Day
cock-a-hoop
  • Exultant; jubilant; triumphant; on the high horse.
  • Tipsy; slightly intoxicated.
This word may come from the phrase 'to set cock on hoop,' or 'to drink festively.' Its origin otherwise is unclear. A theory, according to the Word Detective, is that it's a 'transliteration of the French phrase 'coq a huppe,' meaning a rooster displaying its crest ('huppe') in a pose of proud defiance.' Therefore, 'cock-a-hoop' would 'liken a drunken man to a boastful and aggressive rooster.'
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