Milky Quartz
Silicon Dioxide (SiO2)
mineral
Category
Igneous, Sedimentary, And Metamorphic
Browse igneous, sedimentary, and metamorphic specimens identified by the Rock Identifier community.
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Raw selenite (gypsum)
Gypsum, CaSO₄·2H₂O; translucent variety selenite
mineral
Carved red coral bead (likely coral or coral-colored resin)
Corallium spp. (precious coral; calcium carbonate, CaCO₃)
gemstone
Fossil shark tooth
Likely fossilized shark tooth, possibly *Carcharocles* or *Otodus* species
fossil
Unidentified Rock Fragment
Unknown
Rock
Clear calcite cleavage fragment
Calcite (calcium carbonate, CaCO₃)
mineral
Polished malachite
Malachite, Cu₂CO₃(OH)₂
mineral
Tumbled quartz-rich pebble
Microcrystalline quartz (SiO₂), possibly milky quartz or chalcedony
mineral
Fossil shark tooth
Likely fossilized shark tooth, possibly Carcharhinus or Otodus species
fossil
Pearl
Pearl; primarily aragonite (CaCO₃) in nacre
gemstone
Amethyst
Amethyst (Silicon Dioxide, SiO2)
mineral
Pearl-bearing oyster shell
Nacreous shell, primarily aragonite (CaCO₃), with natural pearls (calcium-carbonate nacre)
fossil
Quartz (chalcedony variety) or Limestone with Quartz Veins
SiO2 (for Quartz/Chalcedony); CaCO3 (for Limestone)
Mineral or Sedimentary Rock (with mineral inclusions)
Desert rose
Gypsum (selenite) rosette, CaSO₄·2H₂O
mineral
Yellow-green serpentine (likely)
Serpentine-group phyllosilicate, commonly lizardite or antigorite; approximate formula Mg₃Si₂O₅(OH)₄
mineral
Pearl
Nacre (aragonite, CaCO₃, in an organic conchiolin matrix)
gemstone
Tumbled amethyst
Amethyst, purple variety of quartz (SiO₂)
mineral
Banded calcite (likely cave deposit or vein fragment)
Calcite, CaCO₃
mineral
Pearl necklace
Pearl—biogenic calcium carbonate, primarily aragonite (CaCO₃)
gemstone
Likely anthracite coal fragments
Anthracite; predominantly carbon (C), with minor mineral ash
sedimentary
Probable amber fragment
Amber (fossilized plant resin; chiefly amorphous organic resin, commonly dominated by succinite)
gemstone
River Stone / Pebble
Clastic Sediment (composed largely of Quartz, Feldspar, and various rock fragments)
Mineral, Sediment
Tiger’s eye
Quartz variety, primarily silicon dioxide (SiO₂); fibrous quartz pseudomorph after crocidolite asbestos
gemstone
Rhodonite
Rhodonite, manganese inosilicate — MnSiO₃; the specimen may include quartz, feldspar, and black manganese-oxide minerals in the matrix
mineral
Mixed Rock Collection (Pebbles and Stones)
Various geological specimens
igneous, sedimentary, and metamorphic
Chalcedony (Banded/Mottled Variety)
Chalcedony (a cryptocrystalline variety of Quartz, SiO2)
Mineral
Mixed collection of minerals and rocks (Jasper, Carnelian, Granite, and Quartz)
Silicon Dioxide (SiO2) with varying impurities for silicates and igneous aggregates
igneous, sedimentary, and metamorphic
Drill Core Samples (Varied Lithology)
Multi-lithological core samples (containing potential granite, marble, and phyllite/schist sequence)
igneous, sedimentary, and metamorphic
Mixed Rock and Mineral Collection
Various geological specimens
igneous, sedimentary, and metamorphic
Earth
Terra / Earth
igneous, sedimentary, and metamorphic
Crushed Stone / Gravel (Multiple Rock Types)
Lithic fragments (undifferentiated)
Igneous, Sedimentary, and Metamorphic mix
Mixed Gravel and Pebbles
Polylithic Alluvial Aggregate
igneous, sedimentary, and metamorphic mix
Quartz / Quartzite Fragment
Silicon Dioxide (SiO2)
igneous, sedimentary, or metamorphic (mineral-based)
Orange Calcite (likely polished specimen)
Calcite
Mineral
Pyrite
Iron Sulfide (FeS2)
mineral
Pyrite
Iron Sulfide (FeS2)
mineral
Chalcopyrite
Copper Iron Sulfide (CuFeS2)
mineral
Specular Hematite with Quartz and Limonite
Hematite (Fe2O3) with Quartz (SiO2) and Limonite (FeO(OH)·nH2O)
Mineral
Quartz (Milky / Massive Quartz)
Silicon Dioxide (SiO2)
mineral
Milky quartz
Quartz (silicon dioxide, SiO₂)
mineral
Pyrite-bearing rock (likely pyrite-rich schist or massive pyrite)
Pyrite, FeS₂, possibly in a micaceous metamorphic matrix
mineral
Quartz-rich rock, possibly milky quartz or quartzite fragment
Quartz (SiO₂), potentially quartzite if metamorphic
mineral