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Corundum

kuh-RUN-dum
Oxide Minerals

A crystalline form of aluminium oxide and a rock-forming mineral, naturally transparent but colored by transition metal impurities. Its two primary gem varieties are ruby, red from chromium, and sapphire, whose colors depend on which transition metal is present. Pure corundum is defined to have 9.0 on the Mohs scale and can scratch almost all other minerals. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/

Facts
Kind
Mineral 1
Formation Class
Oxide mineral (aluminium oxide), forming in aluminum-rich, silica-poor igneous and metamorphic rocks; its gem varieties, ruby and sapphire, crystallize in these same settings. 1
Chemical Formula
Al2O3 1
Hardness (Mohs)
9 1
Classification
Crystal System
Trigonal (Rhombohedral) 1
Classification
Oxide Mineral 1
Use
Gemstone 1
Use
Industrial and Abrasive 1
Connections

Associated With

Gneiss, Materials

Corundum's own page names gneiss as a host rock in metamorphic terranes.

Source Corundum (Wikipedia)
Marble, Materials

Corundum's own page names some marbles as a host rock in metamorphic terranes.

Source Corundum (Wikipedia)
Mohs Hardness Scale, Concepts

Pure corundum is defined to have 9.0 on the Mohs scale.

Source Corundum (Wikipedia)
Pegmatite, Materials

Corundum's own page states it occurs as large crystals in pegmatites.

Source Corundum (Wikipedia)
Schist, Materials

Corundum's own page names mica schist as a host rock in metamorphic terranes.

Source Corundum (Wikipedia)
Syenite, Materials

Corundum's own page names low-silica syenite intrusives as an igneous occurrence.

Source Corundum (Wikipedia)

Classified As

Oxide Minerals, Subcategories

Crystallizes In System

Trigonal Crystal System, Concepts

In Discipline

Mineralogy, Disciplines
Source Corundum (Wikipedia)
In the Other Atlases

Mineral Species Of

Blue Sapphire

Also in Divinity Atlas: of this mineral species.

Ruby

Also in Divinity Atlas: of this mineral species.

White Sapphire

Also in Divinity Atlas: of this mineral species.

Yellow Sapphire

Also in Divinity Atlas: of this mineral species.

Sources
1. Corundum (Wikipedia)
Wikimedia Foundation
  • Lead section
    Because of corundum's hardness (pure corundum is defined to have 9.0 on the Mohs scale), it can scratch almost all other minerals.
  • Lead section
    Corundum is a crystalline form of aluminium oxide (Al2O3) typically containing traces of iron, titanium, vanadium, and chromium.
  • Corundum (Wikipedia), body text
    Corundum crystallizes with trigonal symmetry in the space group R3c
  • Lead section
    Corundum has two primary gem varieties: ruby and sapphire. Rubies are red due to the presence of chromium, and sapphires exhibit a range of colors depending on what transition metal is present.
  • Associated With: Pegmatite, Article text
    Other occurrences are as masses adjacent to ultramafic intrusives, associated with lamprophyre dikes and as large crystals in pegmatites. It commonly occurs as a detrital mineral in stream and beach sands because of its hardness and resistance to weathering.
  • Associated With: Schist, Occurrence section
    Corundum occurs as a mineral in mica schist, gneiss, and some marbles in metamorphic terranes.
  • Associated With: Gneiss, Occurrence section
    Corundum occurs as a mineral in mica schist, gneiss, and some marbles in metamorphic terranes.
  • Associated With: Marble, Occurrence section
    Corundum occurs as a mineral in mica schist, gneiss, and some marbles in metamorphic terranes.
  • Associated With: Syenite, Occurrence section
    It also occurs in low-silica igneous syenite and nepheline syenite intrusives.
View the Source
Wikidata: Corundum
Wikidata Q131777
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