Rock Identifier
Rough Ruby (Corundum) in Zoisite Matrix (Al2O3 (Aluminum Oxide) with Ca2Al3(SiO4)3(OH)) — mineral
mineral

Rough Ruby (Corundum) in Zoisite Matrix

Al2O3 (Aluminum Oxide) with Ca2Al3(SiO4)3(OH)

Hardness: 9.0 (Ruby) / 6.0-7.0 (Zoisite); Color: Purplish-red with green or white mottling; Luster: Vitreous to sub-adamantine; Crystal Structure: Hexagonal (Trigonal); Cleavage: None (Ruby) / Perfect (Zoisite); Specific Gravity: 3.9-4.1

Hardness
9
Color
Purplish-red with green or white mottling
Luster
Vitreous to sub-adamantine
Identified More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App StoreGoogle Play

Physical properties

Hardness: 9.0 (Ruby) / 6.0-7.0 (Zoisite); Color: Purplish-red with green or white mottling; Luster: Vitreous to sub-adamantine; Crystal Structure: Hexagonal (Trigonal); Cleavage: None (Ruby) / Perfect (Zoisite); Specific Gravity: 3.9-4.1

Formation & geological history

Formed through regional metamorphism or hydrothermal activity where aluminum-rich fluids interact with low-silica rocks. Most commonly found in Pre-Cambrian metamorphic belts, often associated with gabbro or schist.

Uses & applications

Primarily used for lapidary work, ornamental carvings, tumbled stones, and as a collector's specimen. Lower-grade specimens are used in industrial abrasives.

Geological facts

Ruby is the second hardest natural substance on Earth after diamond. While high-quality ruby is a precious gemstone, the opaque variety seen here is often called 'common ruby' or 'ruby-in-zoisite' (Anyolite) when found with green zoisite.

Field identification & locations

Identify in the field by its extreme hardness (cannot be scratched by steel) and distinct purplish-pink 'pigeon blood' hue. Often shows a characteristic granular appearance when found in matrix. Major deposits located in Tanzania, India, and Myanmar.

More like this

Other mineral specimens

Sandstone (with potential mineral staining/concretions) (Arenite (SiO2 based)) — sedimentary

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary
Epidote (Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)) — metamorphic

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic
Nephrite Jade (Nephrite) — Mineral/Rock

Nephrite Jade

Nephrite

Mineral/Rock
Banded Gneiss (River Rock/Pebble) (Gneiss (specifically a banded variety often found as a river rock)) — Metamorphic Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock
Green Apatite on Albite (Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]) — mineral

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral
Epidote (Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)) — mineral

Epidote

Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)

mineral