Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Teal Obsidian
A deep teal glass sold as obsidian; the saturated blue-green color is manufactured and not found in natural volcanic glass.
igneous
Smoky Quartz
The smoky brown to gray variety of quartz, colored by natural irradiation, valued as both a gemstone and crystal specimen.
crystal
Morganite Crystal
The natural crystal form of morganite, the manganese-colored pink-to-peach variety of beryl popular in romantic jewelry.
crystal
Boulder Opal
Precious opal that forms in thin veins within brown ironstone boulders, cut with the host rock left as a natural dark backing.
gemstone
Bi-Color Tourmaline
Tourmaline displaying two distinct colors in a single crystal, a natural color-zoning effect that makes each stone unique.
gemstoneLilac Obsidian
A soft pale-purple glass sold as obsidian; uniform lilac material is essentially always manufactured glass rather than natural volcanic obsidian.
igneousRoyal Blue Obsidian
A deep royal-blue glass sold as obsidian; the rich blue body color is manufactured, unlike natural blue-sheen obsidian whose blue is only a surface effect.
igneousGolden Peacock Obsidian
A natural sheen obsidian showing a warm gold shimmer plus peacock iridescence, caused by aligned nanoparticle layers within black glass.
igneousTripolite
A soft, lightweight siliceous sedimentary rock made of fossil diatom remains, prized as a fine natural abrasive and polishing powder.
sedimentary
Brecciated Jasper
A jasper made of angular fragments naturally cemented back together, typically showing red and brown pieces in a quartz matrix.
sedimentaryTurquoise Obsidian
A vivid turquoise-blue glass sold as obsidian; this bright color is virtually always manufactured rather than natural volcanic glass.
igneousEmerald Green Obsidian
A bright emerald-green glass sold as obsidian; saturated transparent green is manufactured, while rare natural green obsidian is only faintly tinted.
igneous
Petrified Wood
Ancient wood whose organic tissue has been replaced by silica, preserving the grain, rings, and structure of the original tree in stone.
sedimentaryTri-Color Tourmaline
Tourmaline displaying three distinct color zones in a single crystal, a striking natural result of changing growth chemistry.
gemstone
Ruin Marble
A fractured fine-grained limestone whose iron-stained crack networks form natural scenes resembling ruined cities and landscapes.
sedimentaryWatermelon Obsidian
A pink-and-green bicolor glass sold as obsidian; the watermelon coloring is manufactured and does not occur in natural volcanic glass.
igneousAmegreen
A natural bicolor quartz blending amethyst purple with prasiolite green in a single crystal, prized as a metaphysical heart-crown stone.
crystalMint Obsidian
A pale mint-green glass sold as obsidian; most uniform light-green material on the market is manufactured glass rather than natural volcanic obsidian.
igneousCherry Obsidian
A vivid cherry-red glass sold as obsidian; the bright transparent red color is manufactured, as natural obsidian only shows dull red-brown mahogany tones.
igneous
Sinter
A chemical deposit precipitated around hot springs and geysers, either siliceous (geyserite) or calcareous, forming delicate terraces and crusts.
sedimentary
Herkimer Diamond
Exceptionally clear, naturally double-terminated quartz crystals from Herkimer County, New York, prized for their diamond-like brilliance.
crystalSilver Peacock Obsidian
A natural sheen obsidian combining a bright silver shimmer with iridescent peacock colors, all produced by nanoparticle layers in black glass.
igneous
Honduran Opal
Precious opal from Honduras occurring in a dark volcanic matrix, where bright flecks of color flash against a natural black basalt background.
gemstoneStrawberry Obsidian
A pink-red glass sold as obsidian, sometimes with metallic flecks; the strawberry color is manufactured rather than a natural volcanic glass tone.
igneous