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Moss agate pebble, 2.5 cm (1 inch) long
Category Quartz variety
(repeating unit)
Silica, SiO2
Crystal habit Cryptocrystalline silica
Crystal system Rhombohedral Microcrystalline
Cleavage None
Fracture Conchoidal with very sharp edges.
Mohs scale hardness 7
Luster Waxy
Streak White
Specific gravity 2.58-2.64
Refractive index 1.530-1.540
Birefringence up to +0.004 (B-G)
Pleochroism Absent

Agate is a kind of quartz and it is a mineral. Agate can come in many different kinds and colors. Agate deposits are primarily found in large rocks such as boulders. agates take 50 million years to form. It is characterized by colored band patterns inside various rocks. Often, agates are also accompanied by Amethyst deposits inside as well as Quartz-like crystals occurring in larger deposits.[source?]