Gastropod Steinkern (Internal Mold Fossil)
Gastropoda (Class); Internal mold or 'Steinkern' composed of Calcium Carbonate (CaCO3) or Sedimentary matrix
sedimentary
Category
Metamorphic (Localized) Or Sedimentary
Browse metamorphic (localized) or sedimentary specimens identified by the Rock Identifier community.
Chalcedony (or a variety of Chalcedony, likely Agate or Jasper)
Chalcedony (SiO₂)
Mineral (or mineraloid if microcrystalline)
Green Slag Glass (Cullet)
Amorphous Silica (Industrial Glass Byproduct)
Synthetic/Byproduct (Non-igneous, non-sedimentary, non-metamorphic)
Epidote
Epidote (Ca2(Al,Fe)3(SiO4)3(OH))
mineral
Green Quartz (including Prase or Aventurine variants)
Silicon Dioxide (SiO2) with inclusions (likely Actinolite or Chlorite)
mineral
Limonite Pseudomorph after Pyrite
Limonite (FeO(OH)·nH2O) replacing Pyrite (FeS2)
mineral
Sunstone
Aventurine Feldspar ((Ca,Na)(Al,Si)4O8)
mineral
Kyanite (Blue and Green varieties)
Kyanite (Al₂SiO₅)
mineral
Green Aventurine
Silicon Dioxide (SiO2) with Fuchsite inclusions
Mineral (Variety of Quartz)
Green Quartz (Prasiolite)
Silicon Dioxide (SiO2) with trace impurities
mineral
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
Citrine (likely Heat-Treated Amethyst)
Silicon Dioxide (SiO2)
mineral
Fossiliferous Limestone (Red Marble)
Bioclastic Limestone (CaCO3)
sedimentary
Iron-stained Quartz
Silicon Dioxide with Iron Oxide (SiO2 with Limonite/Hematite impurities)
mineral
Limonite-stained Granite
Felsic Plutonic Rock with Hydrated Iron Oxides
igneous
Iron Slag
Anthropogenic Iron Silicate
industrial byproduct
Limestone
Calcareous Sedimentary Rock (CaCO3)
sedimentary
Ocean Jasper
Spherulitic Chalcedony (SiO2)
mineral
Amethyst (Geode Fragment)
Silicon Dioxide (SiO2 with iron impurities)
mineral
Fuchsite
Fuchsite (a variety of Muscovite mica, K(Al,Cr)2(AlSi3O10)(OH)2)
mineral
Basalt with Plagioclase Microphenocrysts
Amygdaloidal or Porphyritic Basalt
igneous
Granite with Orthoclase and Hematite Staining
Phaneritic Felsic Igneous Rock (primarily SiO2 with KAlSi3O8)
igneous
Ocean Jasper
Silicon Dioxide (SiO2) with various inclusions
Mineral (Variety of Quartz)
Epidote
Epidote Group (e.g., Clinozoisite, Epidote, Piemontite), Epidote formula: Ca2(Al,Fe)3(SiO4)3(OH)
Mineral
Diorite
Diorite (intermediate intrusive igneous rock)
igneous
Quartz Geode
Quartz (Silicon Dioxide - SiO2) within a Chalcedony and Limonite shell
sedimentary
Black Tourmaline
Schorl (Na(Fe²⁺)₃Al₆(OH)₄(BO₃)₃Si₆O₁₈)
mineral
Chlorastrolite (Isle Royale Greenstone)
Chlorastrolite (Pumpellyite-(Mg,Fe2+): Ca2MgAl2(Si2O7)(SiO4)(OH)2∙H2O)
mineral
Snowflake Obsidian
Volcanic glass with Cristobalite inclusions (mostly SiO2)
igneous
Tiger's Eye (Rough Slab)
Pseudomorph of Quartz after Crocidolite (SiO2 with Fe-containing inclusions)
mineral
Yellow Quartz Pebble
Silicon Dioxide (SiO2)
mineral
Chert Pebble (Jasperoid/Flint)
Silicon Dioxide (SiO2) - cryptocrystalline quartz
Sedimentary
Smoky Quartz
Quartz (SiO₂)
Mineral
Garnet (Almandine or Spessartine likely)
Garnet Group Minerals (e.g., Almandine Fe3Al2(SiO4)3, Pyrope Mg3Al2(SiO4)3, Spessartine Mn3Al2(SiO4)3)
Mineral
Bronzite
MgSiO3 (Enstatite with 10-30% FeSiO3 in solid solution)
Mineral
Snowflake Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with Cristobalite inclusions)
igneous
Hypersthene
Hypersthene ((Mg,Fe)SiO₃)
Mineral
Rhodonite
Rhodonite (MnSiO3)
Mineral
Botryoidal Chalcedony
Chalcedony (SiO2)
Mineral
Limonite (Iron Ore)
Limonite (FeO(OH)·nH2O)
mineral
Goethite (likely as part of Limonite/Ironstone)
Goethite (α-FeOOH)
Mineral
Jasper
Silicon Dioxide (SiO2) - a variety of Chalcedony (Cryptocrystalline Quartz)
Mineral