Cornubite
A variety of Minerals
What is Cornubite?
Cornubite is a rare secondary copper arsenate mineral with formula: Cu5(AsO4)2(OH)4. It was first described for its discovery in 1958 in Wheal Carpenter, Gwinear, Cornwall, England, UK. The name is from Cornubia, the medieval Latin name for Cornwall. It is a dimorph of Cornwallite, and the arsenic analogue of pseudomalachite.
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Cornubite before comparing listings or appraisals.
Size & Weight
Larger, intact specimens usually command higher prices.
Rarity & Demand
Scarce material or popular varieties sell at a premium.
Condition & Finish
Chips, repairs, and heavy wear lower value; clean prep helps.
Treatment & Provenance
Untreated specimens with documented locality are prized.
Cornubite Localities Map
See where Cornubite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
Key Characteristics
Characteristics of Cornubite
Cleavage is distinct in two directions, both perpendicular to the enlarged faces of the tabular crystals, intersecting at about 70°. Cornubite is fairly soft, with hardness 4, the same as fluorite, and specific gravity 4.64, which is similar to another copper arsenate, clinoclase, at 4.38, but much denser than quartz, at 2.66.
Composition of Cornubite
The structure is made up of sheets of edge-shared Cu(O,OH)6 octahedra, with a copper atom Cu in the middle of the octahedron and either oxygen O or hydroxyl OH at each of the six vertices. These sheets are connected together by AsO4 groups with an arsenic As atom in the middle and O at each of the four vertices. In the AsO4 groups three of the O's are shared with octahedra in one octahedral sheet, and the fourth O is shared with an octahedron in the adjacent sheet. Hydrogen bonds also connect the sheets together.
Quick Facts
Physical Properties
- Color
- Apple green, Light to dark green
- Hardness (Mohs)
- 4
- Density
- 4.85 g/cm³
- Streak
- Pale green
Chemical Properties
- Chemical Formula
- Cu5(AsO4)2(OH)4
- Elements
- As, Cu, H, O
Also Known As
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Cornubite FAQs
How do I identify Cornubite?
Cornubite can be identified by its hardness of 4 on the Mohs scale, Apple green color. Look for these key characteristics when examining specimens.
What color is Cornubite?
Cornubite typically appears in Apple green, Light to dark green. Color can vary depending on impurities and formation conditions.
How hard is Cornubite?
Cornubite has a hardness of 4 on the Mohs scale. This gives it moderate hardness.
What is the characteristics of cornubite of Cornubite?
Cleavage is distinct in two directions, both perpendicular to the enlarged faces of the tabular crystals, intersecting at about 70°. Cornubite is fairly soft, with hardness 4, the same as fluorite, and specific gravity 4.64, which is similar to another copper arsenate, clinoclase, at 4.38, but much denser than quartz, at 2.66.
What is the composition of cornubite of Cornubite?
The structure is made up of sheets of edge-shared Cu(O,OH)6 octahedra, with a copper atom Cu in the middle of the octahedron and either oxygen O or hydroxyl OH at each of the six vertices. These sheets are connected together by AsO4 groups with an arsenic As atom in the middle and O at each of the four vertices. In the AsO4 groups three of the O's are shared with octahedra in one octahedral sheet, and the fourth O is shared with an octahedron in the adjacent sheet. Hydrogen bonds also connect the sheets together.
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