Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Sapphire
The gem variety of corundum in every color except red, most prized in velvety blue and exceptionally hard and durable.
gemstone
Blue Sapphire
The blue gem variety of corundum, prized for its rich color, extreme hardness, and brilliance second only to diamond.
gemstone
Yellow-Green Obsidian
A chartreuse yellow-green glass sold as obsidian; the bright color is manufactured and does not occur in natural volcanic glass.
igneous
Yellow Garnet
A trade term for yellow garnets, including golden grossular, yellow andradite (topazolite), and yellow-green Mali garnet.
gemstone
Lime Green Tourmaline
A bright, fresh lime to yellowish-green elbaite tourmaline (verdelite), colored by iron and trace manganese for a lively spring-green tone.
gemstone
Ruby
The red, chromium-colored variety of corundum, prized as one of the most valuable colored gemstones and second only to diamond in hardness.
gemstone
Ruby in Zoisite
A striking rock of green zoisite studded with red-pink ruby crystals and black hornblende, also called anyolite.
metamorphic
Emerald in Matrix
Natural emerald crystals still embedded in their host rock, prized as mineral specimens that show how the gem grew in place.
gemstone
Titanite
A calcium titanium silicate, gem-known as sphene, famous for fiery dispersion that exceeds diamond and rich green-to-yellow colors.
gemstone
Mali Garnet
A rare grossular-andradite blend ('grandite') from Mali, prized for its high brilliance and golden-green to yellow color.
gemstone
Lemon Quartz
A vivid greenish-yellow quartz, usually heat-treated or irradiated, prized for its clean clarity and bright lemon color.
crystal
Imperial Garnet
A trade name for high-brilliance golden grossular-andradite (grandite) garnet, most associated with the Mali deposits of West Africa.
gemstone
Topazolite Garnet
A rare yellow to golden variety of andradite garnet, the topaz-colored cousin of green demantoid, prized for high dispersion and brilliance.
gemstone
Pyromorphite
A lead phosphate secondary mineral known for barrel-shaped green to yellow crystals formed in oxidized lead deposits.
mineral
Prehnite
A translucent yellow-green silicate famous for its botryoidal 'grape' clusters, often hosting needle-like sprays of black epidote.
mineralMacusanite
A rare translucent yellow-green volcanic glass from the Macusani region of Peru, valued by faceters and sometimes confused with tektites.
igneousCat's Eye Opal
An opal cut to show chatoyancy, a sharp moving band of light like a cat's eye, usually in honey, green or yellow common opal.
gemstone
Smithsonite
Smithsonite is a zinc carbonate ore famous for glassy botryoidal crusts in blue-green, pink, and yellow hues.
mineral
Olive Tourmaline
An earthy olive to yellowish-green tourmaline, a muted green-brown gem variety colored by iron with subtle warm undertones.
gemstoneTsilaisite
A manganese-dominant tourmaline, the source of bright yellow to greenish-yellow gem tourmaline, named for its Madagascar type locality.
mineral
Ocean Jasper
A multicolored orbicular chalcedony from Madagascar famous for its circular eye-like orbs in greens, pinks, whites, and yellows.
sedimentary