Amethyst
Amethyst (Silicon Dioxide - SiO2 with impurities of iron)
mineral
Category
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Browse this image does not display a rock, mineral, or geological specimen. it shows a human hand wearing a ring. specimens identified by the Rock Identifier community.
Rhodonite
Rhodonite (Manganese Iron Magnesium Calcium Silicate) - (Mn,Fe,Mg,Ca)SiO3
Mineral
Granite River Rock
Phaneritic Felsic Igneous Rock (Granite)
igneous
Rutilated Quartz
SiO2 with TiO2 inclusions
Mineral
Chert (Field Stone/Jasper variety)
Microcrystalline Quartz (SiO2)
sedimentary
Moss Agate
Silicon Dioxide with inclusions (SiO2 + Fe/Mn/Mg)
mineral
Cupronickel (on a 1981 Mexico 20 Pesos coin)
Copper-Nickel Alloy (Cu75Ni25)
mineral
Gneiss (Metamorphic Cobble)
Gneiss (High-grade Regional Metamorphic Rock)
metamorphic
Fulgurite
Fulgurite (Lechatelierite-rich fused silica)
mineraloid / sedimentary (secondary formation)
Chert (Jasper/Mudstone)
Silicon Dioxide (SiO2)
sedimentary
Picture Jasper
Silicon Dioxide (SiO2) - Microcrystalline Quartz
sedimentary
Jasper (Iron-rich Chert)
Silicon Dioxide (SiO2) with impurities of Hematite or Goethite
sedimentary
Quartzite
Quartzite (SiO2)
metamorphic
Yellow Jasper
Silicon Dioxide (SiO2) with high iron inclusion
sedimentary
Fluorite (often called Rainbow Fluorite or Purple-Green Fluorite)
Calcium Fluoride (CaF2)
mineral
Black Tourmaline
Schorl (NaFe3Al6(BO3)3Si6O18(OH)4)
mineral
Jasper (Yellow/Brown variety)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
sedimentary
Red Jasper (with Quartz inclusions)
Silicon Dioxide (SiO2)
sedimentary (physico-chemical)
Quartzite
Quartzite (SiO2)
metamorphic
Bumblebee Jasper
Volcanic Tuff (mixture of Quartz, Sulfur, Hematite, and Orpiment)
igneous
Anthracite Coal
Anthracite (Carbon-rich metamorphic coal)
sedimentary
Sandstone (with Lichen)
Arenite (primarily SiO2)
sedimentary
Quartz Geode (with Calcite influence)
Silicon Dioxide (SiO2) with possible Calcium Carbonate (CaCO3)
mineral
Moss Agate
Silicon Dioxide (SiO2) with inclusions of manganese or iron oxides
mineral
Red Quartzite (River Stone)
Quartzite (primarily SiO2)
metamorphic
Obsidian Arrowhead
Volcanic Glass (70% or more SiO2)
Igneous
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2)
metamorphic
Petrified Wood
Silicified Wood (SiO2)
sedimentary
Green Quartzite (Aventurine variety)
Silicon Dioxide (SiO2) with inclusions of Fuchsite
metamorphic
Dinosaur Fossil (Skull)
Dinosauria fossilis (Petrified Hydroxyapatite / Calcium Carbonate)
sedimentary
Obsidian
Obsidian (Volcanic Glass)
igneous
Arkosic Sandstone (or Conglomeritic Sandstone fragment)
Arkose (rich in feldspar)
sedimentary
Opalite
Man-made Glass (SiO2 + additives)
mineraloid (synthetic)
Gold
Native Gold (Au)
mineral
River Pebble (Siltstone/Mudstone)
Clastic sedimentary rock
sedimentary
Jasper and Basalt (Mixed Breccia or Chert)
Silicon Dioxide (SiO2) with Ferromagnesian silicates
sedimentary and igneous (mixed)
Opalite (Synthetic Moonstone/Opal)
Synthetic Silica Glass
mineraloid (synthetic)
Red Quartzite
Quartzite (primarily SiO2)
metamorphic
Chert (Cherty Limestone or Flint)
Microcrystalline Silica (SiO2)
sedimentary
Chert (Iron-stained)
Chert (Microcrystalline Quartz, SiO2)
sedimentary
Carnelian
Chalcedony (Silicon Dioxide, SiO2)
mineral
Jasper
Silicon dioxide (SiO2) with iron oxide impurities
sedimentary