Quartz-rich gneiss
Banded quartz–feldspar–mica gneiss; commonly containing biotite and muscovite
Category
Browse sedimentary (man made) specimens identified by the Rock Identifier community.
Quartz-rich gneiss
Banded quartz–feldspar–mica gneiss; commonly containing biotite and muscovite
Chert Concretion / Nodule
Microcrystalline Quartz (SiO2)
Flint
Chert (SiO2)
Limestone
Calcium Carbonate (CaCO3)
Mixed River Stones and Agates
Mixed Silicates and Ironstones (primarily SiO2 and Fe2O3)
Chert (and Flint)
Silicon Dioxide (SiO2)
Sand Dollar Fossil (Echinoidea)
Class Echinoidea (likely order Clypeasteroida), CaCO3 (Calcite)
Emerald
Beryl (Be3Al2(SiO3)6) with Chromium/Vanadium impurities
Limestone Gravel
Sedimentary Calcium Carbonate (CaCO3)
Chert (specifically Flint or Dark Chalcedony)
Silicon Dioxide (SiO2)
Red Jasper
Silicon Dioxide (SiO2) with Hematite (Fe2O3) inclusions
Black-and-white jasper
Jasper, microcrystalline quartz (SiO₂), with contrasting white mineral inclusions
Yellow Jasper
Silicon Dioxide with Limonite (SiO2 + FeO(OH)·nH2O)
Hematite (Iron Ore)
Hematite (Fe2O3)
Weathered flint or chert fragment
Microcrystalline quartz (SiO₂), likely chert/flint
Banded gneiss pebble
Foliated gneiss, typically quartz–feldspar–mica bearing
Carnelian Agate
Carnelian (Silicon Dioxide - SiO2)
Quartz (Rock Crystal) with minor impurities
Quartz (SiO2)
Tumbled yellow calcite
Calcite (calcium carbonate, CaCO₃)
Chert (Smooth River Stone)
Microcrystalline or cryptocrystalline Quartz (SiO2)
Tumbled brown jasper (likely iron-rich chalcedony)
Jasper, opaque microcrystalline quartz (SiO₂), commonly colored by iron oxides
Polished carnelian (reddish-brown chalcedony)
Carnelian, a microcrystalline variety of quartz (SiO₂)
Chert (Holey Stone)
Microcrystalline Quartz (SiO2)
Granitic Gneiss
Gneiss (High-grade Metamorphic Rock)
Orange calcite (honey calcite)
Calcite, calcium carbonate (CaCO₃)
Red Jasper
Silicon Dioxide with Iron Oxide (SiO2 + Fe2O3)
Brown Jasper (Chert)
Silicon Dioxide (SiO2)
Chert (often called Flint when dark)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Tumbled epidote-bearing rock (likely epidote–quartz–feldspar aggregate)
Epidote-rich metamorphic rock; minerals likely epidote (Ca₂(Al,Fe)₃Si₃O₁₂(OH), quartz, feldspar, and dark amphibole/biotite)
Note on Image Identification: Textile
N/A (Anthropogenic material)
Ferruginous Sandstone
Sandstone, Iron-rich
Quartz (likely Rose Quartz or Milky Quartz based on color)
Quartz (SiO2 - Silicon Dioxide)
Quartz
Quartz (Silicon Dioxide - SiO2)
Chert (Fossiliferous)
Silicon dioxide (SiO2)
Botryoidal Chalcedony (Quartz Var.)
Silicon Dioxide (SiO2)
Gneiss
Gneiss
Chert (variations include Flint or Jasper)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
Red Sandstone
Arenite (SiO2 with Fe2O3)
Gneiss
Feldspathic biotite gneiss; a high-grade metamorphic rock composed mainly of quartz, feldspar, and mica
Pale green calcite
Calcite (CaCO₃), likely crystalline limestone or calcite-rich material
Amber with dark mineral/organic inclusions
Fossilized plant resin (amber; chiefly polymerized diterpenoid resin)
Quartz druzy geode
Quartz, silicon dioxide (SiO₂), microcrystalline/druzy variety