Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Double Flow Obsidian
Obsidian formed from two merged lava flows, producing a stone with two distinct bands of sheen or color.
igneousElectric Blue Obsidian
Obsidian with a vivid blue sheen or hue; natural blue obsidian is rare, and intensely uniform blue material is usually manufactured glass.
igneous
Banded Obsidian
Volcanic glass marked by parallel or swirling bands of differing color that record the flow layering of cooling lava.
igneousBronze Sheen Obsidian
Black volcanic glass with a warm bronze or coppery sheen produced by light reflecting off aligned microscopic inclusions.
igneous
Brown Obsidian
Obsidian colored brown by iron oxide inclusions, frequently banded or swirled with black as in mahogany obsidian.
igneousCloudy Obsidian
Obsidian with a hazy, cloud-like translucency caused by uneven distribution of tiny bubbles or incipient crystallites in the glass.
igneous
Garnierite
A vivid green hydrous nickel-magnesium silicate that is a major ore of nickel, mined from weathered ultramafic rocks.
mineralIridescent Obsidian
A black volcanic glass that displays shifting rainbow or metallic sheen from microscopic nanoparticle layers trapped inside.
igneous
Rhyolite
A fine-grained, silica-rich volcanic rock that is the extrusive equivalent of granite, often pale, banded, or flow-textured.
igneous
White Obsidian
A pale, partly crystallized volcanic glass; genuinely white obsidian is uncommon and usually reflects devitrification or spherulitic growth in the glass.
igneous
Porphyritic Obsidian
Natural volcanic glass speckled with embedded mineral crystals (phenocrysts) such as feldspar or cristobalite that grew before the lava chilled.
igneous
Harzburgite
A depleted mantle peridotite of olivine and orthopyroxene, the refractory residue left after basaltic melt is extracted from the mantle.
igneous
Mexican Fire Opal
A transparent to translucent opal prized for its glowing orange-to-red body color, mined chiefly in the volcanic highlands of Mexico.
gemstone
Kimberlite
A rare ultramafic volcanic rock that erupts from deep in the mantle and is the primary natural source of diamonds.
igneous
Breccia
A coarse rock of angular, sharp-edged fragments cemented in a matrix, marking nearby rockfall, faulting, or impact.
sedimentary
Lamproite
A rare ultrapotassic, magnesium-rich volcanic rock from deep in the mantle, famous as the diamond host at Argyle in Australia.
igneous
Purple Obsidian
Purple-colored volcanic glass; genuine natural purple obsidian is rare, with much purple obsidian being manufactured colored glass.
crystalRainforest Jasper
An Australian green rhyolite with eye-like orbs and earthy patterns marketed as jasper, evoking dense rainforest foliage.
igneous
Bumblebee Jasper
A vivid yellow-and-black banded stone from Indonesian volcanic vents, colored by sulfur, arsenic minerals and iron oxides, not true jasper.
sedimentary
Chlorite Schist
A soft, green, foliated rock rich in chlorite, formed by low-grade metamorphism of mafic or volcanic rocks.
metamorphic