Indigo Gabbro is a coarse-grained plutonic igneous rock composed mainly of plagioclase feldspar and pyroxene, with accessory olivine, amphiboles, and oxides. It shows a mottled black, gray, and indigo-purple appearance, with hardness around 6–7 Mohs, white streak, and SG ~3. It is found primarily in Madagascar for the gem market and used in lapidary and decorative work.

An iron sulfide mineral commonly referred to as fools gold.

An iron sulfide mineral commonly referred to as fools gold.

An iron sulfide mineral commonly referred to as fools gold.

An iron sulfide mineral commonly referred to as fools gold.

An iron sulfide mineral commonly referred to as fools gold.