Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Mocha Agate
A pale translucent chalcedony threaded with brown-black manganese and iron dendrites that mimic tiny ferns, mosses or landscapes.
gemstone
Apache Tears
Rounded nodules of translucent obsidian, named after a Native American legend, that glow smoky brown when held to light.
igneous
Lithic Sandstone
A sandstone in which the dominant grains are fragments of pre-existing rocks rather than single minerals, signaling rapid erosion nearby.
sedimentary
Pyromorphite
A lead phosphate secondary mineral known for barrel-shaped green to yellow crystals formed in oxidized lead deposits.
mineral
Brookite
An orthorhombic titanium dioxide polymorph forming tabular brown to black crystals with brilliant metallic-adamantine luster.
mineral
Honey Calcite
A warm golden-to-amber variety of calcite, a soft calcium carbonate mineral valued for its honeyed glow and easy carving.
mineral
Brown Obsidian
Obsidian colored brown by iron oxide inclusions, frequently banded or swirled with black as in mahogany obsidian.
igneous
Buergerite
A rare iron-rich (ferric) species of the tourmaline group, dark brown to bronze-black, named after crystallographer Martin Buerger.
mineral
Lake Michigan Agate
Glacially deposited banded agates found along Lake Michigan beaches, small waterworn pebbles with concentric red and grey banding.
gemstoneLake Huron Agate
Glacially transported banded agates found along Lake Huron's shores, typically small, frosted pebbles with red-orange iron banding.
gemstone
Moss Agate
A translucent chalcedony filled with green or brown dendritic mineral inclusions that resemble moss, foliage, or landscapes.
gemstoneStarry Night Obsidian
Black volcanic glass dotted with small light-colored mineral specks resembling stars scattered across a night sky.
igneous
Brecciated Jasper
A jasper made of angular fragments naturally cemented back together, typically showing red and brown pieces in a quartz matrix.
sedimentary
Orange Tourmaline
A warm orange to tangerine tourmaline, an uncommon hue produced by manganese and iron in the crystal.
gemstone
Siderite
Siderite is an iron carbonate ore, a brown rhombohedral mineral of the calcite group found in sediments and veins.
mineral
Orange Garnet
A trade term for orange garnets, mainly manganese-rich spessartine and the brownish hessonite variety of grossular.
gemstoneHells Canyon Jasper
A warm earth-toned jasper from the Hells Canyon region of the Oregon-Idaho border, prized for brecciated browns, reds, and creams.
gemstone
Honey Garnet
A warm golden-brown garnet named for its honey color, typically a hessonite grossular variety with a distinctive treacly internal texture.
gemstone
Sperrylite
A rare platinum arsenide and the most important platinum-bearing mineral, forming bright metallic cubic crystals.
mineral
Goethite
Goethite is a common brown iron oxyhydroxide, the main crystalline component of limonite and rust, with shimmering botryoidal forms.
mineral
Limonite
Limonite is an amorphous brown iron oxide ore, the rust-colored material behind ochre pigments and bog iron.
mineral
Sherry Tourmaline
A warm sherry-brown to orange-brown tourmaline, usually magnesium-rich dravite, named for its rich fortified-wine color.
gemstone
Pumpkin Obsidian
An orange-to-rust colored variety of natural volcanic glass whose warm tone comes from iron oxide staining within the obsidian.
igneousSardonyx
A banded chalcedony combining reddish-brown sard with white or black onyx layers, prized since antiquity for carved cameos.
gemstone