Rock & Mineral Encyclopedia

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

Columbite

A black iron-manganese niobate that is a primary ore of niobium, forming a continuous series with tantalite (together called coltan).

Iron-stained sandstone whose red color comes from hematite coatings, formed in oxidizing desert, river, and coastal environments.

A vivid yellow-and-black banded stone from Indonesian volcanic vents, colored by sulfur, arsenic minerals and iron oxides, not true jasper.

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

An earthy aluminum-rich residual rock and the world's principal ore of aluminum, often showing distinctive pea-like pisolites.

A classic Oregon picture jasper showing layered tan, brown, and blue-grey scenes resembling desert landscapes and canyons.

A picture jasper from the Owyhee region of Oregon and Idaho, prized for scenic tan, cream, and blue-grey landscape patterns.

A feldspar gemstone that sparkles with metallic glints (aventurescence) caused by tiny reflective copper or hematite platelets.