Agate (or Banded Agate)
Agate (a variety of Chalcedony, which is a cryptocrystalline form of Quartz); Chemical Formula: SiO₂ (Silicon Dioxide)
Mineral, specifically a Cryptocrystalline Quartz variety
Category
Basalt
Browse basalt specimens identified by the Rock Identifier community.
Chalcedony (Banded/Mottled Variety)
Chalcedony (a cryptocrystalline variety of Quartz, SiO2)
Mineral
Quartz Geode (likely within Limestone or Dolomite matrix)
Quartz (SiO₂)
Mineral within a Sedimentary Rock
Sapphire
Corundum (Al₂O₃) with trace elements causing color variations.
Mineral
Epidote (or Epidote-rich rock)
Epidote. Mineral formula: Ca2(Al,Fe)3(SiO4)3(OH).
Mineral, often found in metamorphic rocks but also in sedimentary and igneous rocks
Amethyst Geode/Cluster
Quartz (SiO2) - variety Amethyst
Mineral
Sapphire (likely blue synthetic sapphire or blue glass in a ring)
Corundum (Al₂O₃), specifically the blue variety due to trace amounts of iron and titanium impurities. If synthetic, it would still be Al₂O₃.
Mineral
Note: The image provided is a fabric sock, not a geological specimen.
Polyester-Cotton Blend with Elastane
Synthetic/Natural Fiber (Non-Geological)
Fossilized Stingray Mouth Plate
Myliobatidae dental battery
sedimentary
River Cobble (likely Sandstone or Siltstone type)
Sandstone or Siltstone (common rock types that form river cobbles)
Sedimentary Rock (specifically a clastic sedimentary rock formed into a cobble)