
mineral
Specular Hematite and Magnetite Ore
Iron Oxide (Fe2O3 and Fe3O4)
Hardness: 5.5-6.5 (Mohs scale); Color: Steel grey to black with metallic silver glitter; Luster: Sub-metallic to metallic; Crystal Structure: Rhombohedral; Specific Gravity: 5.2-5.3; Streak: Cherry red to reddish-brown.
- Hardness
- 5
- Color
- Steel grey to black with metallic silver glitter
- Luster
- Sub-metallic to metallic
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Physical properties
Hardness: 5.5-6.5 (Mohs scale); Color: Steel grey to black with metallic silver glitter; Luster: Sub-metallic to metallic; Crystal Structure: Rhombohedral; Specific Gravity: 5.2-5.3; Streak: Cherry red to reddish-brown.
Formation & geological history
Formed primarily in banded iron formations (BIFs) through chemical precipitation in ancient oceans or via hydrothermal replacement and metamorphism of iron-rich sediments, typically dating from the Proterozoic eon.
Uses & applications
Primary source of iron for steel manufacturing; also used for heavy media separation, pigments, and balance weights. High-grade specularite is often sought after for mineral specimen collections.
Geological facts
Specularite gets its name from 'speculum' (Latin for mirror) because it was once used as a reflective surface. It is often mildly magnetic if it contains trace amounts of magnetite, which is common in massive iron ore samples like this.
Field identification & locations
Identify in the field by its high density (feels heavy for its size) and by doing a streak test on unglazed porcelain—hematite will leave a distinctive red/brown streak regardless of its dark grey surface color.
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