Analcime (/əˈnælsiːm, -saɪm/; from Ancient Greek ἀνάλκιμος (análkimos) 'not strong') or analcite is a white, gray, or colorless tectosilicate mineral.

Analcime consists of hydrated sodium aluminium silicate in cubic crystalline form.

It was first described by French geologist Déodat de Dolomieu, who called it zéolithe dure, meaning hard zeolite.

The mineral is IMA approved, and had been grandfathered, meaning the name analcime is believed to refer to a valid species til this day.

[2] The mineral usually has polysynthetic twins, which are only visible in thin sections when the specimen is inspected under polarized analyzed light.

[4] Analcime mainly consists of oxygen (50.87%), silicon (25.51%), aluminum (12.26%), sodium (10.44%) but otherwise has a negligible amount of hydrogen (0.92%) as well.

Of the pinkish-white specimens, the mineral takes the shape of well-formed cubes which can exceed 10 cm, originating from several sites in Val di Fassa, Trentino, Italy.

[4] Well known locations for sourcing analcime include Croft Quarry in Leicestershire, UK; the Cyclopean Islands east off Sicily and near Trentino in northern Italy; Victoria in Australia; Kerguelen Island in the Indian Ocean; in the Lake Superior copper district of Michigan, Bergen Hill, New Jersey, Golden, Colorado, and at Searles Lake, California in the United States; and at Cape Blomidon, Nova Scotia and Mont Saint-Hilaire, Quebec[1] in Canada; and in Iceland, and in Namibia.

This is due to the fact that analcime has a compact structure and thus it has a strong resistance to diffusion of both molecules and cations.