Rock & Mineral Encyclopedia

Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.

Niccolite

A pale copper-red nickel arsenide, historically called kupfernickel, that is an ore of nickel and gives the metal its name.

A nickel sulfide famous for delicate brass-yellow hairlike crystals that form radiating sprays inside cavities and geodes.

A vivid green hydrous nickel-magnesium silicate that is a major ore of nickel, mined from weathered ultramafic rocks.

A translucent apple-green chalcedony colored by nickel, the most prized green variety of the quartz family.

A common opal colored green by nickel or chromium impurities, usually opaque and cut into cabochons and beads.

A metallic cobalt-nickel arsenide, an important cobalt ore, named for the Skutterud mines of Norway.

A bronze-colored iron sulfide notable for being the most magnetic of the common sulfide minerals and an important nickel host.

A vivid green chalcedony colored by chromium, often called mtorolite, resembling chrysoprase but owing its color to chromium rather than nickel.

A high-grade metamorphic rock defined by alternating light and dark mineral bands, formed under intense heat and pressure.