Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Zincite
A rare zinc oxide best known for its deep red to orange color, classically from Franklin, New Jersey, and as colorful man-made crystals.
mineral
Deschutes Jasper
A prized Oregon picture jasper from the Deschutes region known for soft scenic landscapes in cream, tan, and blue-gray.
mineral
Malachite
A vivid green copper carbonate mineral famous for swirling concentric bands, used as an ore of copper and an ornamental gemstone.
mineral
Tantalite
A dense black iron-manganese tantalate that is the chief ore of tantalum, forming a series with columbite and mined as coltan.
mineral
Bauxite
An earthy aluminum-rich residual rock and the world's principal ore of aluminum, often showing distinctive pea-like pisolites.
sedimentary
Limonite
Limonite is an amorphous brown iron oxide ore, the rust-colored material behind ochre pigments and bog iron.
mineral
Uraninite
Uraninite is the chief radioactive uranium ore, a dense black oxide and the historic source of radium and uranium.
mineral
Goethite
Goethite is a common brown iron oxyhydroxide, the main crystalline component of limonite and rust, with shimmering botryoidal forms.
mineral
Garnierite
A vivid green hydrous nickel-magnesium silicate that is a major ore of nickel, mined from weathered ultramafic rocks.
mineral
Tetrahedrite
A gray copper-antimony sulfosalt of the fahlore group, an important ore of copper and often silver, forming tetrahedral crystals.
mineralGary Green Jasper
An Oregon jasper, also called larsonite, of silicified fossil wood showing olive-green fields laced with black dendritic patterns.
mineral
Sunstone
A feldspar gemstone that sparkles with metallic glints (aventurescence) caused by tiny reflective copper or hematite platelets.
gemstone
Sphalerite
Zinc sulfide and the chief ore of zinc, prized when transparent for its extreme fire that exceeds diamond.
mineral
Cobaltite
A silver-white cobalt arsenic sulfide that is a leading ore of cobalt, forming bright metallic cubic and pyritohedral crystals.
mineral
Hyalophane
A barium-bearing potassium feldspar intermediate between orthoclase and celsian, found in barium-rich metamorphic and ore deposits.
mineral
Dumortierite Quartz
Quartz colored blue by inclusions of the mineral dumortierite, giving a denim-like blue ornamental stone harder than dumortierite alone.
gemstone
Phantom Quartz
Quartz containing visible internal crystal outlines, formed when growth paused and trapped a layer of mineral inclusions.
crystal
London Blue Topaz
The deepest, most saturated blue grade of treated topaz, prized for its rich steely-blue color and durability in jewelry.
gemstone
Matrix Opal
Opal in which precious play-of-color is intimately dispersed through the pores of its host rock rather than forming a solid seam.
gemstoneGrape Garnet
A trademarked deep purple-red rhodolite garnet from India, named for its rich grape-like color from the pyrope-almandine series.
gemstone
Covellite
A soft copper sulfide famous for its intense indigo-blue color and dazzling iridescent metallic sheen, prized by collectors.
mineralFancy Jasper
A soft-toned, multicolored jasper with swirling green, mauve, and cream patterns, popular and affordable in the bead trade.
sedimentary
Monazite
A reddish-brown rare-earth phosphate that is a primary ore of cerium, thorium and other rare-earth elements, often found in placer sands.
mineral
Rutile
Rutile is a major titanium ore and the famous golden needle inclusion that gives rutilated quartz its shimmering threads.
mineral