Quartzite
Quartzite (primarily SiO2)
metamorphic
Category
Organic (Often Found By Beachcombers)
Browse organic (often found by beachcombers) specimens identified by the Rock Identifier community.
Sodalite
Na8(Al6Si6O24)Cl2
mineral
Chert
Microcrystalline Quartz (SiO2)
sedimentary
Quartzite with Feldspar
Quartzite (mainly SiO2) with inclusions of Potassium Feldspar (KAlSi3O8)
metamorphic
Quartzite
Quartzite (SiO2)
metamorphic
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
mineral
Variscite in Matrix
Variscite (AlPO4 · 2H2O)
mineral
Orange Quartz with Hematite inclusions
Quartz (SiO2) with Hematite (Fe2O3) inclusions
Mineral
Carnelian Agate
Silicon Dioxide (SiO2) with iron oxide impurities
mineral
Basalt Porphyry
Porphyritic Basalt
igneous
Rose Quartz
Silicon Dioxide (SiO2)
mineral
Greenstone Celt (Polished Stone Axe)
Metamorphosed mafic rock (often Basalt or Diabase)
metamorphic
River Cobble (likely Basalt or Chert)
Siliceous River Rock / Microcrystalline Quartz / Mafic Igneous
igneous/sedimentary
Blue Apatite
Fluorapatite (Ca5(PO4)3F)
mineral
Selenite (Satin Spar)
Gypsum (CaSO4·2H2O)
mineral
Chalk
CaCO3 (primarily Calcium Carbonate), biogenic sedimentary rock
Sedimentary
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Quartz (River Pebble)
Silicon Dioxide (SiO2)
mineral
Yellow Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Quartz (Iron-stained)
Silicon Dioxide (SiO2)
mineral
Chert (Grey-Green Flint)
Microcrystalline silicon dioxide (SiO2)
sedimentary
Jade (Nephrite or Jadeite)
Nephrite (Ca2(Mg,Fe)5Si8O22(OH)2) or Jadeite (Na(Al,Fe3+)Si2O6)
Mineral
Serpentine
Serpentinite (group of minerals: (Mg,Fe,Ni,Al,Zn,Mn)2-3(Si,Al,Fe)2O5(OH)4)
metamorphic
Limestone
CaCO3 (principally Calcite)
sedimentary
Rhyolite
Rhyolite (Extrusive Igneous Rock)
igneous
Hematite
Iron(III) oxide (Fe2O3)
mineral
Hematite
Iron(III) oxide (Fe2O3)
mineral
Fossil Coral
Cnidaria fossil (often Calcium Carbonate / CaCO3)
sedimentary
Limonite after Pyrite (Prophecy Stone or Ironstone Concretion)
Goethite/Limonite pseudomorph after Pyrite/Marcasite (FeO(OH)·nH2O)
mineral
African Turquoise (Jasper)
Silicon Dioxide (SiO2) - Macro-crystalline Quartz with inclusions
sedimentary
Ammonite Fossil
Ammonoidea (Calcium carbonate or Pyrite replaced)
sedimentary
Dendrite (Manganese Oxide Dendrites)
Psilomelane or Pyrolusite on Matrix (typically MnO2)
mineral
Silicon Carbide (Carborundum)
Moissanite (SiC), though mostly synthetic
mineral
Arsenopyrite with Schist Matrix
Arsenopyrite (FeAsS)
mineral
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Red Jasper (Banded Jasper)
Silicon Dioxide (SiO2) with Hematite impurities
sedimentary
Agate Geode
Banded Chalcedony (Silicon Dioxide, SiO2) with Quartz crystals
mineral
Fluorite
Calcium Fluoride (CaF2)
mineral
Fire Agate (Rough)
Silicon Dioxide (SiO2) - Variety of Chalcedony
mineral
Diorite (Salt and Pepper Rock)
Diorite
igneous
Chert (and associated Sedimentary rocks)
Microcrystalline Silica (SiO2)
sedimentary
Green Sea Glass
Amorphous Silica (man-made glass), SiO2 + additive metal oxides
mineraloid / anthropogenic (man-made origin)