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Material

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

Entity-backed identity for the material classification this material already carries as an enum fact, pointing at the class subcategory of the same name. The enum fact itself stays on the entity unchanged.

Crystallizes In System

Trigonal Crystal System, Concepts

Entity-backed identity for the crystal-system enum value this material already carries, resolved to an earth concept by an explicit value-to-entity map (phase 3 bucket conversion, docs\design_entity_backed_browse_buckets_20260928.md). The crystal-system fact itself stays on the material unchanged.

In Discipline

Mineralogy, Disciplines
Source Corundum (Wikipedia)
In the Other Atlases
  • Also in Divinity Atlas: Blue Sapphire, mineral species of there.
  • Also in Divinity Atlas: Ruby, mineral species of there.
  • Also in Divinity Atlas: White Sapphire, mineral species of there.
  • Also in Divinity Atlas: Yellow Sapphire, mineral species of there.
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.
  • Entity classification (SubLabel)
    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 sapph
  • Corundum (Wikipedia), body text
    Corundum crystallizes with trigonal symmetry in the space group R3c
  • Corundum, live entity-description
    Its two primary gem varieties are ruby, red from chromium, and sapphire
  • Associated With: Pegmatite, Occurrence section
    The mineral also appears as masses adjacent to ultramafic intrusives, associated with lamprophyre dikes and as large crystals in pegmatites.
  • 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
Quote, Wikidata Q131777
P279 subclass chain verified to reach rock (Q8063) or mineral (Q7946) within a few hops; identified via Wikipedia pageprops (article title match), PlaybookNote 38526.
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