Rock & Mineral Encyclopedia

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

Feather Jasper

A jasper marked with soft feather- or plume-like mineral inclusions that drift through a pale silica body.

A chalcedony agate marked by round, concentric ring patterns that resemble eyes when cut and polished.

A soft, lightweight, chalky sedimentary rock made of the silica shells of microscopic diatoms, prized for its absorbency and filtering ability.

An Australian silicified radiolarite jasper in warm mustard, red, burgundy, and cream earth tones, found only in Western Australia.

An Oregon jasper, also called larsonite, of silicified fossil wood showing olive-green fields laced with black dendritic patterns.

Ilmenite is the world's leading source of titanium, a heavy iron-black oxide common in mafic rocks and black sands.

Goethite is a common brown iron oxyhydroxide, the main crystalline component of limonite and rust, with shimmering botryoidal forms.

An umbrella term for green members of the garnet group, including prized tsavorite, demantoid, and rare chrome-rich uvarovite.

A hollow rock nodule whose interior cavity is lined with inward-pointing crystals such as quartz, amethyst, or calcite.

The most common type of mantle peridotite, made of olivine with both orthopyroxene and clinopyroxene, representing fertile upper-mantle rock.

A dark, highly vesicular volcanic rock full of gas bubbles, denser than pumice, common as red or black lava rock.

An opaque blue variety of chalcedony jasper, less common than red or green forms, colored by mineral inclusions.

A common potassium feldspar identical in composition to orthoclase but more ordered, famous for its green gem variety amazonite.