Rock & Mineral Encyclopedia

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

Glauconite

A soft, green iron-potassium mica that forms in marine sediments and gives greensand its characteristic olive color.

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

A fine-grained clastic rock of silt-sized grains, intermediate between sandstone and mudstone, with a gritty feel.

A foliated metamorphic rock dominated by quartz with enough mica to give it a schistose, splitting fabric.