Limestone
Calcium Carbonate (CaCO3)
sedimentary
Category
Organic (Often Found By Beachcombers)
Browse organic (often found by beachcombers) specimens identified by the Rock Identifier community.
Red Jasper
Silicon Dioxide with Iron Oxide (SiO2)
sedimentary
Quartzite (River Pebble)
Metamorphosed Quartz Sandstone (SiO2)
metamorphic
Smoky Quartz
Silicon Dioxide (SiO2) with aluminum impurities
mineral
Unakite
Epidotized Granite (SiO2 with Ca2(Al, Fe)3(SiO4)3(OH))
metamorphic
Smoky Quartz
Smoky Quartz (Silicon Dioxide, SiO2)
mineral
Gold Nugget Jewelry
Native Gold (Au)
mineral
Arsenopyrite in Quartz Matrix
Arsenopyrite (FeAsS) with Quartz (SiO2)
Mineral in a Metamorphic/Hydrothermal rock
Rhodonite
Manganese Inosilicate (Mn,Fe,Mg,Ca)SiO3
mineral
Baltic Amber (Butterscotch or Egg Yolk Variety)
Fossilized Tree Resin (Succinite); Approximate formula: C10H16O
Organic Gemstone (Succinite)
Brown Jasper
Jasper (a cryptocrystalline variety of Quartz, SiO2)
Mineral, specifically a variety of Quartz
Ferruginous Quartz
Silicon Dioxide (SiO2) with Hematite (Fe2O3) inclusions
mineral
Chert (Flint)
Silicon Dioxide (SiO2)
sedimentary
Quartzite
Quartzite (primarily SiO2)
metamorphic
Amethyst
Silicon Dioxide (SiO2) with Iron impurities
mineral
Pink Quartzite
Quartzite (primarily SiO2)
metamorphic
Peridotite (with Olivine)
Peridotite (rich in Olivine, (Mg,Fe)2SiO4)
igneous
Satin Spar (often marketed as Selenite)
Fibrous Gypsum (CaSO4·2H2O)
mineral
Quartzite (or Quartz Rich Conglomerate)
Quartzite (SiO2 silicon dioxide)
metamorphic
Quartzite
Quartzite (SiO2)
metamorphic
Beach Quartzite Pebble
Quartzite (primarily SiO2)
metamorphic
Sandstone with Quartz Vein
Arenite with Quartz (SiO2) Infilling
sedimentary
Quartzite
Quartzite (SiO2)
metamorphic
Basalt
Basalt (SiO2 percentage between 45% and 52%)
igneous
Satin Spar (Gypsum)
Hydrous Calcium Sulfate (CaSO4·2H2O)
mineral
Quartz Vein in Host Rock
Silicon Dioxide (SiO2) in matrix
Mineral in Metamorphic/Igneous Host
Yellow Calcite
Calcium Carbonate (CaCO3)
mineral
Prehnite
Prehnite (Ca2Al(AlSi3O10)(OH)2)
mineral
White Moonstone (Scolicite or White Feldspar var. )
Lattice-structure Silicate (KAlSi3O8)
mineral
Lepidolite
K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2
mineral
Prehnite
Prehnite (Ca2Al(AlSi3O10)(OH)2)
mineral
Rose Quartz
Silicon Dioxide (SiO2) with trace Titanium, Manganese or Iron
mineral
Celestite (Celestine) Geode
Strontium Sulfate (SrSO4)
mineral
Drill Core Sample
Cylindrical Rock Core (Specific mineralogy varies by extraction site)
Metamorphic (Likely Gneiss or Schist based on texture)
Obsidian (Black Obsidian)
Obsidian (Volcanic Glass)
igneous
Rough Aquamarine
Beryl (Be₃Al₂Si₆O‑₁•H₂O)
Mineral
Ferruginous Quartz
Quartz (Silicon Dioxide) with Iron Inclusion (SiO2 + Fe2O3)
mineral
Diorite (Porphyritic)
Porphyritic Diorite
igneous
Yellow Jasper (Iron-stained Quartzite/Chert)
Silicon Dioxide (SiO2) with Hydrated Iron Oxide (Goehite/Limonite) inclusions
sedimentary
Chert (Flint nodule)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Chert / Flint
Microcrystalline or cryptocrystalline quartz (SiO2)
sedimentary
Coral Fossil (Favosites type)
Phylum Cnidaria, Class Anthozoa (often CaCO3 - Calcium Carbonate)
sedimentary