Agate is a common rock formation, consisting of chalcedony and quartz as its primary components, with a wide variety of colors. Agates are primarily formed within volcanic and metamorphic rocks.
Crystal habit Cryptocrystalline silica
Fracture Conchoidal with very sharp edges
Mohs scale hardness 6.5–7
Specific gravity 2.58–2.64
Refractive index 1.530–1.540