igneous
Brown Antique Granite
Anorthosite (Technically a plutonic rock composed mainly of plagioclase feldspar)
Hardness: 6-7 on Mohs scale; Color: Dark brown to black background with iridescent bronze, chocolate, and copper-colored crystals; Luster: Vitreous to pearly on crystal faces; Crystal Structure: Phaneritic (coarse-grained); Cleavage: Perfect in two directions for feldspar components.
- Hardness
- 6-7 on Mohs scale
- Luster
- Vitreous to pearly on crystal faces
Identified More igneous →
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Dark brown to black background with iridescent bronze, chocolate, and copper-colored crystals; Luster: Vitreous to pearly on crystal faces; Crystal Structure: Phaneritic (coarse-grained); Cleavage: Perfect in two directions for feldspar components.
Formation & geological history
Formed through the slow cooling and crystallization of molten magma deep beneath the Earth's crust (plutonic). This specific type is often sourced from Precambrian-aged rock formations (over 500 million years old) in regions like Angola or Brazil.
Uses & applications
Extensively used for high-end residential and commercial construction, specifically kitchen countertops, bathroom vanities, flooring, and exterior wall cladding due to its durability and aesthetic appeal.
Geological facts
While marketed as granite in the stone industry, it is geologically an anorthosite. The shimmering effect is caused by the schiller effect or labradorescence in large feldspar crystals, reflecting light in a metallic dance.
Field identification & locations
Identified in the field by its very coarse grain size and the presence of large, 'flashing' crystals of plagioclase feldspar set in a dark mafic matrix. Collectors look for pieces with high 'labradorescence' or copper-colored flashes.
