Opal
Hydrated Amorphous Silica (SiO2·nH2O)
Category
Browse mineral, possibly rock fragment containing a mineral specimens identified by the Rock Identifier community.
Opal
Hydrated Amorphous Silica (SiO2·nH2O)
Sandstone (Quartzose)
Arenite (composed primarily of SiO2)
Granite Pegmatite with Tourmaline and Muscovite
Pegmatite (Feldspar: KAlSi3O8, Quartz: SiO2, Schorl: NaFe2+3Al6(Si6O18)(BO3)3(OH)3(OH))
Rutilated Quartz
Quartz (SiO2) with Rutile (TiO2) inclusions
Banded Calcite (often sold as 'Mexican Onyx' or 'Calcite Onyx')
Calcite (Calcium Carbonate, CaCO3)
Quartz
Silicon Dioxide (SiO2)
Fossiliferous Limestone
Calcium Carbonate - CaCO3
Fossiliferous Limestone with Brachiopod Mold
Calcium Carbonate (CaCO3) matrix containing Brachiopoda fossil impressions
Gold Ore
Auriferous Quartz and Sulfide Mineralization in Host Rock
Schist
Mica Schist
Fossilized Coral
Scleractinia (fossil order), primarily Calcium Carbonate (CaCO3)
Mica Schist
Mica Schist (Intermediate-grade Metamorphic Rock)
Basalt
Basalt (Aphanitic mafic volcanic rock)
Geode (unopened)
Calcedony-lined Geode (SiO2)
Diorite (River Cobble)
Intermediate plutonic igneous rock
Milky Quartz with Iron Staining
Silicon Dioxide (SiO2)
Milky Quartz Vein with Iron Staining
Silicon Dioxide (SiO2)
Chert (Nodule)
Silicon Dioxide (SiO2)
Sandstone (Quartzose Sandstone)
Arenite (primarily SiO2 with minor Fe2O3)
Greywacke (River Slikkenstone)
Greywacke (Impure Sandstone)
Gold Nugget
Native Gold (Au)
Red Sandstone
Arenite (with Iron Oxide cement)
Red Sandstone
Clastic sedimentary rock (primarily SiO2 with Fe2O3)
Calamites (Fossilized Horsetail)
Calamites suckowii (Family: Calamitaceae)
Basalt
Mafic Igneous Rock
Que Sera Stone (Llanite)
Rhyolite Porphyry with Blue Quartz and Feldspar
Quartz / River Cobble
Silicon Dioxide (SiO2)
Quartz (possibly Citrine or Smoky Quartz variety)
Silicon Dioxide (SiO2)
Common Opal with Host Rock
Opal (Hydrated silica, SiO2·nH2O)
Petrified Wood
Silicified Wood (primarily Chalcedony or Quartz, SiO2)
Bumble Bee Jasper
Volcanic Tuff (mixture of SiO2, CaCo3, S, and As2S3)
Tree Agate (or Moss Agate)
Dendritic Agate (Silicon Dioxide - SiO2)
Quartz (Crystal Point/Fragment)
Silicon Dioxide (SiO2)
Common Opal in Host Rock
Hydrated Silica (SiO2·nH2O)
Amygdaloidal Rhyolite
Amygdaloidal Rhyolite (Felsic volcanic rock)
Tufa (Limestone)
Calcareous Tufa (CaCO3)
Granitic Pegmatite with Biotite
Pegmatitic Granite (contains KAlSi3O8, SiO2, K(Mg,Fe)3AlSi3O10(OH)2)
Gneiss
Gneiss (High-grade Metamorphic Rock)
Ferruginous Quartz (Iron-stained Quartz)
Quartz with Iron Oxide inclusions (SiO2 with Fe2O3)
Pegmatite (White Granite variant)
Pegmatitic Granite (Quartz and Feldspar rich)
Gneiss (Schistose)
Gneiss
Green Aventurine
Aventurine Quartz (SiO2 with inclusions of Fuchsite)