Caledonite, whose name derives from Caledonia, the historical name of its place of discovery (Scotland), is a richly colored blue-green sulfate-carbonate mineral of lead and copper with an orthorhombic crystal structure.

It is an uncommon mineral found in the oxidized zones of copper-lead deposits.

Although it contains copper and lead, it is a secondary mineral and is not prevalent enough in any known deposits to be used as an ore. Caledonite, when developed into full crystals, can have a deep blue-green color reminiscent of secondary copper minerals.

Frequently associated minerals include: linarite, malachite, cerussite, brochantite, anglesite, leadhillite, and azurite.

Useful tests for determining if a specimen is caledonite include its density, streak, and crystal habit.