mineral
Agate
Cryptocrystalline quartz, SiO2
Hardness 6.5-7 on Mohs scale, highly variable color with banding, waxy or vitreous luster, cryptocrystalline structure, conchoidal fracture, specific gravity 2.58-2.64. The blue color in this specimen might be dyed.
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Physical properties
Hardness 6.5-7 on Mohs scale, highly variable color with banding, waxy or vitreous luster, cryptocrystalline structure, conchoidal fracture, specific gravity 2.58-2.64. The blue color in this specimen might be dyed.
Formation & geological history
Forms by the deposition of silica from groundwater in cavities of igneous rocks, resulting in rhythmic bands of varying composition.
Uses & applications
Used primarily in lapidary arts, jewelry, decorative items, and sometimes as a healing or spiritual stone.
Geological facts
Agate was named by Theophrastus, a Greek philosopher and naturalist, who discovered the stone along the shoreline of the Achates River in Sicily.
Field identification & locations
Identify by its waxy luster, hardness (can scratch glass), and distinctive banding patterns. Found worldwide, often in areas with volcanic activity.
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Other mineral specimens
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Sandstone with Mineral Veining or Crust
Sedimentary Sandstone (mostly SiO2 with Fe2O3 tinting)
sedimentary
Schist
Schist
Metamorphic
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Nephrite Jade
Nephrite
Mineral/Rock