Yellow Chalcedony (Agate)
Silicon Dioxide (SiO2)
mineral
Category
Not A Geological Specimen
Browse not a geological specimen specimens identified by the Rock Identifier community.
Granitic Pegmatite
Granite (with coarse-grained Quartz, Feldspar, and Mica components)
igneous
Jasper
Silicon dioxide (SiO2)
sedimentary
Granite Cobble
Granite (Phaneritic Igneous Rock)
igneous
Granite (weathered)
Felsic Intrusive Igneous Rock (composed of Quartz, Alkali Feldspar, and Plagioclase)
igneous
Black Tourmaline in Quartz Matrix
Schorl (NaFe3Al6(BO3)3Si6O18(OH)4) with Quartz (SiO2)
mineral
River Pebble (Siltstone/Mudstone)
Clastic sedimentary rock
sedimentary
Amber
Succinite (a specific common type) or Fossilized Tree Resin (C10H16O)
Mineraloid
Banded Agate (Carnelian type)
Agate (Cryptocrystalline Quartz, SiO2)
mineral
Fossil Shark Tooth (Cretaceous white shark type)
Squalicorax (commonly known as Crow Shark)
Organic specimen (fossil)
Calcite on Limestone (or Fossil)
Calcium Carbonate (CaCO3)
sedimentary
Chert (Agatized Chert)
Microcrystalline Quartz (SiO2)
sedimentary
Quartzite (River Pebble)
Meta-quartzite (composed primarily of SiO2)
metamorphic
River Stone / Siltstone
Siltstone (composed of lithified silt)
sedimentary
Cream Marble (Speckled)
Metamorphosed Limestone (mainly CaCO3)
metamorphic
Citrine
Citrine (Silicon Dioxide, SiO2)
mineral
Quartzite with Iron Inclusions
Metamorphosed Quartz Sandstone (SiO2 with Fe2O3)
metamorphic
Dark Igneous Rock (Likely Basalt or Diabase)
Basalt (extrusive igneous rock) or Diabase (intrusive igneous rock - also known as Dolerite), largely composed of plagioclase feldspar, pyroxene (augite), and sometimes olivine and amphibole. Exact mineralogy would require thin section analysis.
Igneous
Amygdaloidal Basalt with Quartz/Zeolite Infill
Amygdaloidal Basalt (extrusive volcanic rock with SiO2 or CaAl2Si3O10·3H2O infill)
igneous
Petrified Wood
Silicified Wood (primarily SiO2)
sedimentary
Agatized Petrified Wood
Silicon Dioxide (SiO2) - Chalcedony pseudomorph after Wood
metamorphic
Petrified Wood
Silicified Wood (SiO2)
mineral
Jasper (yellow/cream variety)
SiO₂ (Cryptocrystalline Quartz)
Sedimentary
Amber
Succinite
mineraloid
Amber
Fossilized Tree Resin (C10H16O)
mineral
Milky Quartz
Quartz (Silicon Dioxide, SiO2)
mineral
Quartz (Milky/Common)
Silicon Dioxide (SiO2)
mineral
Kyanite in Quartz
Al2SiO5 in SiO2
metamorphic
Jasper (Petrified Wood variant)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
sedimentary
Shale with Vein Infillings
Shale (a fine-grained clastic sedimentary rock). The veins could be Calcite (CaCO3), Quartz (SiO2), or other minerals.
Sedimentary Rock
Amber
Succinite (fossilized resin)
mineral
Amber
Succinite (a Fossilized Tree Resin); Chemical formula is approximately C10H16O
Organic mineraloid
Rhyolitic Tuff (Breccia Type)
Rhyolitic Pyroclastic Rock (Mixed Silicates including Quartz, Feldspar, and Volcanic Glass)
igneous
Chert (Common Opal/Jasper variety)
Silicon Dioxide (SiO2)
sedimentary
Copper Ore with Malachite and Chrysocolla
Cu2CO3(OH)2 (Malachite) with Cu2-xAlx(H2-xSi2O5)(OH)4·nH2O (Chrysocolla)
mineral
Sandstone (Pebble)
Sandstone (arenite, arkose, wacke depending on composition)
sedimentary
Fluorite (specifically Rainbow Fluorite or Purple Fluorite)
Calcium Fluoride (CaF2)
mineral
Gastropod Internal Mold (Steinkern)
Class Gastropoda fossil mold (Phylum Mollusca)
sedimentary
Blue Lace Agate (often dyed)
Silicon dioxide (SiO2) - variety of chalcedony
mineral
Agate (Chert/Chalcedony)
Silicon Dioxide (SiO2)
mineral
Sandstone (likely Siltstone)
Arenite or Siltstone (high SiO2 content)
sedimentary
Milky Quartz
Silicon Dioxide (SiO2)
mineral