October 2025 – Zaratite

The rare mineral zaratite stands out due to its intense emerald green color. It owes this color to its high nickel content. Although it is also known as “nickel emerald,” it is not a real emerald, but rather a carbonate mineral (chemical formula: Ni₃[(OH)₄|CO₃] · 4H₂O).

Zaratite is formed secondarily when nickel-bearing rocks weather on the earth’s surface. Nickel is deposited in fine crusts, grains, or veins. It often occurs together with other nickel minerals such as garnierite or annabergite. Due to its rarity and usually low hardness, zaratite is not suitable as a gemstone, but is highly prized by collectors. Its bright green color made it a sought-after exhibit in natural history collections in the 19th century.

Chemical formula: Ni₃[(OH)₄|CO₃] · 4H₂O

Location: Texas, Lancaster Co., Pennsylvania, USA