Rock & Mineral Encyclopedia

Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.

Siderite

Siderite is an iron carbonate ore, a brown rhombohedral mineral of the calcite group found in sediments and veins.

An Oregon picture jasper from the Rogue River area showing earthy scenic patterns in tan, brown, gold, and cream.

The principal iron ore, a heavy iron oxide ranging from metallic silver-gray to earthy red, always leaving a tell-tale red-brown streak.

An orthorhombic titanium dioxide polymorph forming tabular brown to black crystals with brilliant metallic-adamantine luster.

An altered granite of pink feldspar, green epidote and quartz, mottled pink-and-green and popular as a tumbled and carving stone.

The warm cinnamon-to-honey-brown variety of grossular garnet, also known as hessonite, with a characteristic swirly internal texture.

Glacially transported banded agates found along Lake Huron's shores, typically small, frosted pebbles with red-orange iron banding.

Black volcanic glass crossed by a fine network of grey or brown veins that resemble a spider's web.

A reddish-brown rare-earth phosphate that is a primary ore of cerium, thorium and other rare-earth elements, often found in placer sands.

A gray-toned jasper with swirling cream, black, and brown leaf-like patterns, sometimes with druzy or agate pockets.

A translucent chalcedony filled with green or brown dendritic mineral inclusions that resemble moss, foliage, or landscapes.

A gray-brown jasper whose mottled, wrinkled patterning resembles elephant hide, also sold as Miriam or calligraphy stone.

A prized Idaho picture jasper from Bruneau Canyon known for brown and cream orbicular egg-rock patterns and scenic landscapes.