Prehnite
Calcium aluminum silicate hydroxide - Ca2Al(AlSi3O10)(OH)2
Category
Browse sedimentary (volcanic) specimens identified by the Rock Identifier community.
Prehnite
Calcium aluminum silicate hydroxide - Ca2Al(AlSi3O10)(OH)2
Bloodstone / Heliotrope
Silicon dioxide (SiO2) with inclusions
Mahogany Obsidian or Red Jasper
Silicon Dioxide with Iron Oxide (SiO2+Fe2O3)
Andesite
Andesite (Intermediate Extrusive Volcanic Rock)
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with impurities)
Basalt
Mafic volcanic rock (primarily Plagioclase and Pyroxene)
Sandstone
Arenite (SiO2 predominantly)
Sandstone (likely Arkosic)
Clastic Sedimentary Rock (primarily SiO2 with Feldspar)
Diorite (Salt and Pepper Rock)
Phaneritic Plutonic Diorite (Plagioclase Feldspar + Amphibole/Biotite)
Obsidian
Obsidian (Amorphous Volcanic Glass, SiO2)
Basalt
Basalt (Aphanitic mafic volcanic rock)
Sandstone or Mudstone
Sedimentary Rock (Sandstone/Mudstone)
Obsidian
Volcanic glass (SiO2 - Silicon Dioxide with impurities)
Gold Sheen Obsidian
Volcanic Glass (Amorphous Silica with Magnetite inclusions)
Obsidian
Volcanic glass (high silica content based on SiO2)
Basalt (River Pebble)
Mafic volcanic rock (primarily Plagioclase feldspar and Pyroxene)
Stilbite
Stilbite-Ca (NaCa4(Si27Al9)O72·28H2O)
Amethyst
Silicon Dioxide (SiO2) with iron impurities
Larimar
Pectolite (NaCa2Si3O8(OH))
Amethyst
Silicon Dioxide (SiO2) with trivalent iron (Fe3+) impurities
Crazy Lace Agate
Silicon Dioxide (SiO2) - Chalcedony variety
Turquoise
Hydrated phosphate of copper and aluminium (CuAl6(PO4)4(OH)8·4H2O)
Prehnite
Prehnite (Ca2Al2Si3O10(OH)2)
Ocean Jasper
Silicon Dioxide (SiO2) - Orbicular Jasper / Chalcedony
Carnelian (Chalcedony)
Silicon Dioxide (SiO2)
Sulfur on Quartz
Native Sulfur (S8) with Quartz (SiO2)
Banded Agate
Agate (Cryptocrystalline variety of Quartz, SiO2)
Specular Hematite
Specularite (Iron Oxide, Fe2O3)
Diorite (with Quartz veins)
Diorite
Prehnite
Prehnite (Ca2Al(AlSi3O10)(OH)2)
Diorite
Diorite
Diorite
Diorite (Intermediate intrusive igneous rock)
Nuummite
Nuummite (ortho-amphibole rock)
Diorite
Diorite (Intermediate intrusive igneous rock)
Dendritic Opal (Merlinite)
Hydrated Silica with Manganese/Iron oxide inclusions (SiO2·nH2O)
Peridotite (Olivine)
Peridotite (comprising (Mg,Fe)2SiO4)
Amethyst
Amethyst (SiO2 with iron impurities)
Diamond (in jewelry)
Diamond (Carbon, C)
Green Banded Agate
Agate (Variety of Chalcedony/Quartz), SiO2
Black Onyx
Chalcedony (SiO2) with parallel banding
Arsenopyrite
Arsenopyrite (FeAsS)
Milky Quartz with Chlorite/Mica inclusions
Silicon Dioxide (SiO2) with phyllosilicate inclusions