Quartz
Quartz (SiO2 - Silicon Dioxide)
Mineral, often found as detrital grains in sedimentary rocks
Category
Synthetic Polymer (Polylactic Acid)
Browse synthetic polymer (polylactic acid) specimens identified by the Rock Identifier community.
Learn about Synthetic Polymer (Polylactic Acid) in the encyclopedia
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Sodalite
Sodalite - Na8(Al6Si6O24)Cl2
Mineral
Blue Quartzite
Quartzite (specifically a variety enriched with blue-coloring minerals)
Metamorphic Rock
Banded Chert or Chert with Quartz Veins
Chert (SiO2)
Sedimentary
Fossil Coral
Fossilized Scleractinia or Tabulata (various genera/species)
Sedimentary
Sandstone
Arenite or Sandstone
Sedimentary Rock
Quartz
Quartz (SiO₂ - Silicon Dioxide)
mineral
Fossiliferous Limestone
Limestone (composed primarily of calcite with included fossils CaCO3)
Sedimentary
Quartz
Quartz (SiO2 - Silicon Dioxide)
Mineral
Cobaltoan Calcite / Pink Dolomite (Possible)
Cobaltoan Calcite: (Ca,Co)CO3; Pink Dolomite (or Thulite): CaMg(CO3)2 or Mn-Dolomite / (Thulite: Mn2+3Al2(Si2O7)(SiO4)O(OH))
Mineral / Rock (depending on purity)
Unidentified Rock Fragment
Unknown
Rock
Basalt
Basalt (dominated by plagioclase feldspar and pyroxene)
igneous
Fossil Coral
Coral Limestone (a type of biogenic sedimentary rock)
Sedimentary
Quartz (chalcedony variety) or Limestone with Quartz Veins
SiO2 (for Quartz/Chalcedony); CaCO3 (for Limestone)
Mineral or Sedimentary Rock (with mineral inclusions)
Sandstone (with possibly iron oxides and other minerals)
Sandstone
Sedimentary rock
Weathered Volcanic Rock (possibly Rhyolite or Andesite Pebble)
Volcanic rock (e.g., Rhyolite or Andesite, specific identification would require thin section analysis or chemical assay). Mineral composition: Primarily feldspars (orthoclase and/or plagioclase), quartz (in rhyolite), micas, amphiboles, and sometimes pyroxenes.
Igneous, specifically volcanic/extrusive (possibly Rhyolite or Andesite)
Fluorite
Fluorite (CaF₂)
mineral
Fluorite
Fluorite (Calcium Fluoride, CaF2)
mineral
Fluorite
Fluorite (Calcium Fluoride, CaF2)
mineral
Red Swirl Beads (Likely Resin or Glass, simulating Red Jasper or Agate)
N/A (for the beads as pictured); Red Jasper: SiO2 (Chert variety); Red Agate: SiO2 (Chalcedony variety)
Organic (if resin) or Synthetic (if glass); simulating Sedimentary or Metamorphic (for natural stones)
Quartzite
Quartzite (primarily composed of SiO O₂)
Sedimentary Rock
Calcite
Calcite (CaCO3)
Mineral
Amphibolite
Amphibolite
metamorphic
Caliche (also known as hardpan, calcrete, kankar)
Primarily composed of calcium carbonate (CaCO₃), often mixed with other minerals like quartz, clay minerals, and iron oxides.
Mineral
Fluorite
Fluorite (Calcium Fluoride, CaF2)
Mineral
Banded Gneiss (Variety of Gneiss)
Gneiss (specifically, a variety exhibiting prominent banding; mineral composition can vary, but often contains quartz, feldspar, mica, and amphibole)
Metamorphic Rock
Dark-colored Igneous Rock (likely Basalt or Diabase)
Basalt (extrusive igneous) or Diabase (intrusive igneous)
Igneous Rock
Calcite (or Alabaster, if truly carved)
Calcium Carbonate (CaCO3)
Mineral/Rock
Puddingstone
Polymictic Conglomerate
sedimentary
Conglomerate
Polymictic Conglomerate
sedimentary
Puddingstone
Polymictic Conglomerate
sedimentary
Conglomerate
Conglomeratic Sandstone / Polymictic Conglomerate
sedimentary
Obsidian with Spherulitic Devitrification (Snowflake Obsidian/Mahogany related)
Volcanic Glass (70% or more SiO2)
igneous
Chert
Microcrystalline Quartz (SiO2)
sedimentary
Specular Hematite (Specularite)
Iron Oxide (Fe2O3)
mineral
Red Jasper
Microcrystalline Quartz (SiO2) with Hematite inclusions
sedimentary
Quartz (Iron-stained)
Silicon Dioxide (SiO2)
mineral
Serpentinite
Serpentinite (group of minerals: Antigorite, Lizardite, Chrysotile)
metamorphic
Ferruginous Quartz
Silicon Dioxide with Hematite/Limonite inclusions (SiO2 + Fe2O3)
mineral
Quartz (Small Fragment)
Silicon Dioxide (SiO2)
mineral
Basalt (Vesicular)
Mafic Volcanic Rock (rich in Magnesium and Iron)
Igneous
Desert Varnish on Sandstone
Ferromanganese coating on Quartz Arenite
sedimentary