How do I identify Theophrastite?

Theophrastite can be identified by its hardness of 3.5 on the Mohs scale, Emerald Green color. Look for these key characteristics when examining specimens.

What color is Theophrastite?

Theophrastite typically appears in Emerald Green. Color can vary depending on impurities and formation conditions.

How hard is Theophrastite?

Theophrastite has a hardness of 3.5 on the Mohs scale. This gives it moderate hardness.

Theophrastite

A variety of Minerals

What is Theophrastite?

Nickel(II) hydroxide is the inorganic compound with the formula Ni(OH)2. It is an apple-green solid that dissolves with decomposition in ammonia and amines and is attacked by acids. It is electroactive, being converted to the Ni(III) oxy-hydroxide, leading to widespread applications in rechargeable batteries.

Theophrastite Market Value Calculator

Estimate the market value of Theophrastite using size, quality, and finish. This preview calculator is for quick context and is not a formal appraisal.

Theophrastite Localities Map

See where Theophrastite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.

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North ZoneCentral RidgeSouth Basin

Key Characteristics

Characteristics of Theophrastite

Nickel(II) hydroxide has two well-characterized polymorphs, α and β. The α structure consists of Ni(OH)2 layers with intercalated anions or water. The β form adopts a hexagonal close-packed structure of Ni and OH ions. In the presence of water, the α polymorph typically recrystallizes to the β form. In addition to the α and β polymorphs, several γ nickel hydroxides have been described, distinguished by crystal structures with much larger inter-sheet distances. The mineral form of Ni(OH)2, theophrastite, was first identified in the Vermion region of northern Greece, in 1980. It is found naturally as a translucent emerald-green crystal formed in thin sheets near the boundaries of idocrase or chlorite crystals. A nickel-magnesium variant of the mineral, (Ni,Mg)(OH)2 had been previously discovered at Hagdale on the island of Unst in Scotland.

Health & Safety Information

⚠️The Ni ion is a known carcinogen. Toxicity and related safety concerns have driven research into increasing the energy density of Ni(OH)2 electrodes, such as the addition of calcium or cobalt hydroxides.