Green Aventurine
Silicon Dioxide (SiO2) with inclusions
metamorphic
Category
Mineral, Specifically A Rock Fragment
Browse mineral, specifically a rock fragment specimens identified by the Rock Identifier community.
Amethyst
Amethyst (Silicon Dioxide, SiO2)
mineral
Wishing Stone (Basalt/Greywacke with Quartz Vein)
Basalt or Siltstone with SiO2 (Quartz) hydrothermal intrusion
igneous/sedimentary
Basalt
Mafic Igneous Rock (primarily Plagioclase Feldspar and Pyroxene)
igneous
Gneiss
Gneiss
metamorphic
Fossilized Shark Tooth (Dermal Denticle or worn tooth fragment)
Elasmobranchii (fossil remains)
sedimentary
Obsidian
Amorphous volcanic glass (primarily SiO2)
igneous
Limonite Concretion
Goethite-rich Concretion (FeO(OH))
sedimentary
Granite featuring Quartz Vein
Granite with hydrothermal silica (SiO2) intrusion
igneous
Green Quartzite
Quartzite (primarily SiO2 with chlorite inclusions)
metamorphic
Kimberlite with Diamond
Kimberlite (Porphyritic Peridotite)
igneous
Quartz (Water-worn pebble)
Silicon Dioxide (SiO2)
mineral
Biotite Mica
Biotite (K(Mg,Fe)3AlSi3O10(F,OH)2)
mineral
Basalt with Caliche Crust
Aphanitic Mafic Igneous Rock with Calcium Carbonate (CaCO3) coating
igneous
Carnelian
Carnelian (SiO2)
mineral
Ferruginous Sandstone
Arenite with Iron-Oxide Cement (FeO(OH)·nH2O / Fe2O3)
sedimentary
Limonite (often after Hematite or Goethite)
Limonite (FeO(OH)·nH2O)
mineral
Banded Gneiss
Gneiss (High-grade Metamorphic Rock)
metamorphic
Garnetiferous Quartzite (Garnet Gneiss Pebble)
Garnet-bearing Quartzite or Quartz-Feldspar Gneiss
metamorphic
Granite
Phaneritic Igneous Rock (Granite)
igneous
Red Sandstone (Iron-Rich)
Arenite (Fe2O3)
sedimentary
Diabase (Dolerite) Cobble
Diabase / Dolerite
igneous
Quartz Geode
Silicon Dioxide (SiO2) within a secondary sedimentary structure
sedimentary
Quartz Vein / Milky Quartz
Silicon Dioxide (SiO2)
mineral
Sandstone (Ferruginous)
Arenite (with Iron Oxide)
sedimentary
Gneiss
Gneiss (High-grade metamorphic rock)
metamorphic
Milky Quartz
Silicon Dioxide (SiO2)
Mineral
Turquoise
Hydrated phosphate of copper and aluminium, CuAl6(PO4)4(OH)8·4H2O
mineral
Snowflake Obsidian
Spherulitic Volcanic Glass (primarily SiO2 with Cristobalite inclusions)
igneous
Milky Quartz Pebble
Quartz (Silicon Dioxide, SiO2)
mineral
Vuggy Quartz on Matrix
Silicon Dioxide (SiO2)
mineral
Sandstone (likely Quartzose type)
Clastic sedimentary rock (primarily SiO2)
sedimentary
Agate
Silicon dioxide (SiO2)
mineral
Agate
Silicon Dioxide (SiO2) - variety: Chalcedony
mineral
Howlite and Purple Amethyst Druzy
Calcium Borosilicate Hydroxide (Howlite) and Silicon Dioxide (Quartz/Amethyst)
mineral
Sunstone
Plagioclase Feldspar (specifically Oligoclase variety with hematite or goethite inclusions) Chemical Formula: (Ca,Na)(Al,Si)2Si2O8
Mineral
Granite
Phaneritic Felsic Igneous Rock (composed of SiO2, KAlSi3O8, NaAlSi3O8)
igneous
Tree Agate
Silicon Dioxide (SiO2) - Dendritic Agate/Chalcedony
sedimentary
Quartz (Quartzite)
Silicon Dioxide (SiO2)
mineral
Biotite Mica
Biotite (K(Mg,Fe)3AlSi3O10(OH,F)2)
mineral
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Turquoise (set in silver jewelry)
Turquoise - CuAl6(PO4)4(OH)8·4H2O (Hydrated copper and aluminum phosphate)
mineral