Amethyst
Amethyst (Silicon Dioxide, SiO2 with Iron impurities)
mineral
Category
Mineral In A Matrix (Likely Quartz Or Feldspar)
Browse mineral in a matrix (likely quartz or feldspar) specimens identified by the Rock Identifier community.
Dinosaur Bone (Gembone)
Agatized Dinosaur Bone (Silicified Paleo-osteoid)
metamorphic
Quartz Vein in Host Rock
Silicon Dioxide (SiO2) within Matrix
igneous/metamorphic
Sandstone
Arenite (primarily Quartz, SiO2)
sedimentary
Pink Granite
Granite (Felsic Plutonic Rock)
igneous
Granite
Felsic Intrusive Igneous Rock
igneous
Granite Cobble
Phaneritic Felsic Igneous Rock
igneous
Porphyritic Basalt (with Amygdales)
Amygdaloidal Porphyritic Basalt
igneous
Amethyst Geode
Silicon Dioxide (SiO2) - Amethyst variety of Quartz
mineral
Quartzite (River Pebble)
Metamorphosed Quartz Sandstone (SiO2)
metamorphic
Red Granite
Potassium-feldspar rich Granite
igneous
Tiger's Eye (Rough)
Pseudomorph of Quartz after Crocidolite (SiO2 with FeOOH inclusions)
mineral
Pink Orthoclase Feldspar with Dendrites
Orthoclase (KAlSi3O8) with Manganese Oxide dendrites
mineral
Ferruginous Quartz (River Pebble)
Silicon Dioxide (SiO2) with Iron Oxide inclusions
sedimentary (secondary classification for a weathered mineral specimen)
Basalt (Porphyritic Basalt)
Porphyritic Basalt (Mafic volcanic rock)
igneous
Unakite
Epidotized Granite
metamorphic
Amygdaloidal Basalt
Amygdaloidal Basalt (Mafic Volcanic Rock)
igneous
Granite
Granite (Felsic Intrusive)
igneous
Sandstone (Ferruginous)
Arenite (composed primarily of SiO2 with iron oxide Fe2O3 cement)
sedimentary
Pink Granite
Granite (Felsic Plutonic Rock)
igneous
Diorite
Phaneritic Intrusive Igneous Rock (Intermediate Composition)
igneous
Granite
Granite (Phaneritic Quartz-Feldspar Rock)
igneous
Green Aventurine
Silicon Dioxide (Quartz with Fuchsite inclusions), SiO2 + K(Al,Cr)2AlSi3O10(OH)2
mineral
Amygdaloidal Basalt
Vesicular Basalt with secondary mineral infilling (commonly Zeolite, Calcite, or Quartz)
igneous
Turquoise and Red Coral
Turquoise: CuAl6(PO4)4(OH)8·4H2O; Red Coral: Corallium rubrum (organic gemstone)
mineral
Jasper (likely Brecciated or Multi-colored)
Jasper (SiO2)
sedimentary
Ferruginous Sandstone
Sandstone, Iron-rich
sedimentary
Rough Corundum (likely Sapphire/Zircon-bearing)
Aluminium Oxide (Al2O3)
mineral
Quartz Crystal Cluster
Quartz (Silicon Dioxide, SiO2)
mineral
Smoky Quartz (with possible Feldspar inclusions)
Silicon Dioxide (SiO2)
mineral
Porphyritic Basalt (Peanut Obsidian/Star Galaxy-style)
Porphyritic Basalt (Silica-rich Volcanic Rock)
igneous
Granite
Phaneritic Intrusive Igneous Rock (composed of Quartz, Feldspar, and Mica)
igneous
Unakite
Epidotized Granite
Igneous rock
Orthoclase Feldspar
KAlSi3O8 (Potassium Aluminum Silicate)
Mineral
Quartz
Silicon Dioxide (SiO2)
Mineral
Dalmatian Stone (often called Dalmatian Jasper)
Peralkaline Feldsphathic Igneous Rock
igneous
Obsidian
Obsidian (Volcanic Glass)
igneous
Sandstone
Arenite (composed primarily of SiO2)
sedimentary
Granite
Plutonic felsic igneous rock
igneous
Sandstone (Grooved/Weathered)
Arenite (composed primarily of Quartz and Lithic fragments)
sedimentary
Chert (containing Flint and Chalcedony)
Microcrystalline Quartz (SiO2)
sedimentary
Exposed Aggregate Concrete (Pea Gravel)
Concrete with Siliceous Alluvial Gravels
sedimentary (man-made conglomerate)