Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Enhydro Quartz
Quartz containing a sealed pocket of ancient water, often with a mobile air bubble that moves when the crystal is tilted.
crystal
Cactus Quartz
A South African quartz whose central crystal is coated in a cactus-like crust of tiny secondary points, also called spirit quartz.
crystal
Girasol Quartz
A translucent milky quartz that shows a soft, floating blue-white glow when light passes through it.
crystalCandle Quartz
A quartz with a main point surrounded by many smaller crystals along its sides, resembling melted candle wax, mainly from Madagascar.
crystal
Faden Quartz
Tabular quartz crossed by a milky white thread-like line marking where the crystal repeatedly cracked and re-healed.
crystal
Green Quartz
A green variety of macrocrystalline quartz, usually the heat- or radiation-altered prasiolite, prized for its soft mint hue.
crystal
Cathedral Quartz
Quartz with a stepped, multi-pointed structure of parallel side crystals resembling the spires of a cathedral.
crystal
Phantom Quartz
Quartz containing visible internal crystal outlines, formed when growth paused and trapped a layer of mineral inclusions.
crystal
Blue Quartz
A naturally blue quartz colored by tiny mineral inclusions such as dumortierite or scattered rutile and tourmaline fibers.
crystal
Brandberg Amethyst
A prized Namibian quartz combining amethyst, smoky, and clear quartz in single crystals, often with phantoms and enhydros.
crystal
Star Rose Quartz
Rose quartz that displays a six-rayed star (asterism) when cut as a cabochon, caused by microscopic rutile-like inclusions.
gemstone
Golden Healer Quartz
Quartz colored or coated by golden iron oxides such as limonite or goethite, giving a warm sunlit yellow glow.
crystal
Quartz-mica Schist
A foliated metamorphic rock of interlayered quartz and mica, producing a sparkling, easily split rock from metamorphosed sandy shales.
metamorphic
Herkimer Diamond
Exceptionally clear, naturally double-terminated quartz crystals from Herkimer County, New York, prized for their diamond-like brilliance.
crystalSuper Seven
A trade name for quartz containing a combination of seven minerals including amethyst, smoky quartz, and cacoxenite, prized by collectors.
crystal
Greywacke
A hard, dark, poorly sorted sandstone with a muddy matrix, typically deposited by underwater turbidity currents.
sedimentary
Needle Tourmaline
Fine acicular (needle-like) tourmaline crystals, often black schorl, frequently seen as slender inclusions within clear quartz.
mineral
Celestite
A soft, sky-blue strontium sulfate mineral famous for the glittering pale-blue crystal geodes from Madagascar.
mineral
Brecciated Agate
Agate that was shattered and naturally re-cemented by silica, creating a mosaic of angular fragments in a quartz matrix.
gemstoneRegency Rose Agate
A prized plume agate with rose-pink and red feathery inclusions suspended in clear chalcedony, from the western U.S.
gemstoneGraveyard Point Agate
A celebrated plume agate from the Oregon-Idaho border, known for dramatic black, gold, and red plumes in clear chalcedony.
gemstone
Lithic Sandstone
A sandstone in which the dominant grains are fragments of pre-existing rocks rather than single minerals, signaling rapid erosion nearby.
sedimentary
Brecciated Jasper
A jasper made of angular fragments naturally cemented back together, typically showing red and brown pieces in a quartz matrix.
sedimentaryPrase
An old name for a dull leek-green variety of quartz or chalcedony colored by green mineral inclusions, historically called mother of emerald.
crystal