Quartz (Milky Quartz)
Silicon Dioxide (SiO2)
mineral
Category
Organic (Often Found By Beachcombers)
Browse organic (often found by beachcombers) specimens identified by the Rock Identifier community.
Gneiss (Granitic Gneiss)
Gneiss
metamorphic
Sandstone (with potentially metamorphic or basaltic bands)
Arenite / Lithic Wacke
sedimentary
Diopside (likely Chromian Diopside)
Diopside, part of Clinopyroxene family of inosilicates. Chemical formula: CaMgSi2O6. The green variety is often Chromian Diopside due to chromium impurities.
mineral
Quartzite
Quartzite (primarily SiO2)
metamorphic
Serpentinite
Serpentinite (composed primarily of Serpentine group minerals: (Mg, Fe, Ni, Al, Zn, Mn)2-3(Si, Al, Fe)2O5(OH)4)
metamorphic
White Jade (Nephrite)
Nephrite, Ca2(Mg,Fe)5Si8O22(OH)2
Mineral
Iron Meteorite
Iron-nickel alloy (primarily kamacite and taenite)
Mineral/Rock (Extraterrestrial Origin)
Diorite
Diorite (intermediate intrusive igneous rock)
igneous
Fossil Coral (Rugose Coral)
Rugosa (extinct order); typically composed of Calcite (CaCO3) or replaced by Quartz (SiO2)
sedimentary
Ironstone Concretion (Limonite/Goethite)
Ironstone (primarily FeO(OH)·nH2O)
sedimentary
Amethyst (Tumbled Stone)
Amethyst (Silicon Dioxide with Iron impurities, SiO2)
mineral
Chert (Iron-stained)
Microcrystalline Quartz (SiO2)
sedimentary
Limonite with Trace Fossils
Hydrous Iron Oxide Mixture (FeO(OH)·nH2O)
sedimentary
Quartz (River Pebble)
Silicon Dioxide (SiO2)
mineral
Quartzite
Quartzite (primarily Silicon Dioxide, SiO2)
metamorphic
Onyx (Black Onyx)
Silicon Dioxide (SiO2) - Chalcedony variety
Mineral
Quartzite Pebble
Quartzite (primarily SiO2)
metamorphic
Citrine
SiO2 (Silicon Dioxide)
mineral
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Banded Chert
Silicon Dioxide (SiO2)
sedimentary
Chert (White/Gray variety)
Chert (SiO2)
sedimentary
Amazonite
Microcline (KAlSi3O8) with lead impurities
mineral
Chalcopyrite
Chalcopyrite (CuFeS2)
mineral
Nickel coin (U.S. currency)
Cupronickel (75% Copper, 25% Nickel alloy)
man-made alloy (metallic)
Gneiss (specifically a Banded Gneiss cobble)
Gneiss (composed mainly of Quartz, Feldspar, and Biotite/Amphibole)
metamorphic
Quartzite with Iron Inclusions
Metamorphosed Quartz Sandstone (SiO2 with Fe2O3)
metamorphic
Rose Quartz
Silicon Dioxide (SiO2) with trace amounts of titanium, iron, or manganese
mineral
Milky Quartz / Rose Quartz fragment
Silicon Dioxide (SiO2)
mineral
Native Gold (in earring form)
Gold (Au)
mineral
Quartzite
Quartzite (SiO2)
metamorphic
Yellow Jasper
Silicon Dioxide (SiO2) with Goethite/Iron inclusions
sedimentary
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
mineral
Sandstone with Iron Oxide (Limonite/Hematite)
Ferruginous Sandstone (SiO2 with FeO(OH)·nH2O)
sedimentary
Greenstone
Metabasalt / Chlorite-Epidote Schist
metamorphic
Indian Agate
Cryptocrystalline Quartz (SiO2)
mineral
Sunstone
Aventurine Feldspar (Plagioclase Feldspar with inclusions)
mineral
Quartz (Gravel fragment)
Quartz (Silicon Dioxide, SiO2)
mineral
Blue Chalcedony
Silicon Dioxide (SiO2)
mineral
Howlite and Purple Amethyst Druzy
Calcium Borosilicate Hydroxide (Howlite) and Silicon Dioxide (Quartz/Amethyst)
mineral
Rose Quartz
Quartz (Silicon Dioxide, SiO2)
mineral
Fluorite
Calcium Fluoride (CaF2)
mineral