Rock & Mineral Encyclopedia

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

Gray Obsidian

Obsidian in gray tones, often semi-translucent, colored by light scattering and minor inclusions within the volcanic glass.

A dark green chalcedony speckled with blood-red spots of iron oxide, traditionally known as heliotrope.

A vivid Australian jasper-like silica stone in earthy reds, yellows, and purples, formed from silicified radiolarian sediment.

A white to grayish banded chalcedony, the natural base color of much agate and the substrate for many dyed stones.

A common opal containing moss- or fern-like mineral inclusions that resemble plants suspended in a pale silica body.

Translucent smoky-gray obsidian that transmits a hazy light, intermediate between clear and fully black volcanic glass.

A vivid blue-green hydrated copper silicate, soft on its own but prized as a gem when hardened by intergrown quartz or chalcedony.

Opal with a dark grey body tone sitting between black and light opal, giving play-of-color rich contrast at an accessible price.

A soft blue common opal, famously from Peru, valued for its serene sky-to-teal color rather than play-of-color.

A clear, glassy, botryoidal common opal famous for its intense green fluorescence under UV light, caused by trace uranium.

An opaque, iron-rich variety of microcrystalline quartz known for its deep brick-red color and ancient history as a stone of strength and grounding.

A translucent yellow-green silicate famous for its botryoidal 'grape' clusters, often hosting needle-like sprays of black epidote.

A warm earth-toned jasper from Madagascar in flowing reds, oranges and golds, also called desert jasper, discovered in the early 2000s.