Quartz Geode
Silicon Dioxide (SiO2) in Host Rock
sedimentary
Category
Biogenic Material
Browse biogenic material specimens identified by the Rock Identifier community.
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Green Jasper
Jasper (Silicates, SiO2)
sedimentary
Fossilized Brachiopod
Phylum Brachiopoda (replaced by Calcite/CaCO3)
sedimentary
Petrified Wood
Silicified Wood (primarily SiO2)
mineral
Tiger's Eye
SiO2 (Silicon Dioxide with Iron Oxide inclusions)
Mineral (Metamorphic pseudomorph)
Chert (Jasper-bearing)
Microcrystalline silica (SiO2) with iron oxide inclusions
sedimentary
Bivalve Fossil in Sedimentary Matrix
Fossiliferous Mudstone (Class: Bivalvia)
sedimentary
Fossilized Shark Tooth
Bioapatite (Calcium Hydroxyapatite) replacement
mineral
Quartz with impurities or Host Rock
SiO2 (Silicon Dioxide) with mixed silicates
mineral
Chert (Fossiliferous)
Silicon dioxide (SiO2)
sedimentary
Chert (often found as Flint)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Gneiss
Gneissic Metamorphic Rock
metamorphic
Chert (Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Yellow Jasper/Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Yellow Jasper
Silicon Dioxide (SiO2) with iron oxide inclusions
sedimentary
Cullet Glass (Man-made Glass Slag)
Amorphous Silica (SiO2) with chemical additives
Mineraloid
Dark river pebble, likely basalt or fine-grained volcanic rock
Basalt (probable); mostly plagioclase and pyroxene, with possible magnetite
igneous
Limestone (River Pebble)
Calcium Carbonate (CaCO3)
sedimentary
Agatized Fossil or Chalcedony Nodule
Silicon Dioxide (SiO2) - Cryptocrystalline Quartz
sedimentary
Polished jasper pebble
Jasper, microcrystalline quartz (SiO₂), commonly with iron-oxide impurities
metamorphic
Decorative polished pebbles
Likely mixed quartz-rich lithologies, including quartzite, jasper, and/or basalt
mineral
Diamond
Native Carbon (C)
mineral
Fossilized coral or porous marine limestone
Likely fossil coral (Scleractinia), composed mainly of calcite/aragonite (CaCO₃)
fossil
Polished nephrite jade
Nephrite jade; compact amphibole aggregate, chiefly tremolite–actinolite, Ca₂(Mg,Fe)₅Si₈O₂₂(OH)₂
metamorphic
Tumbled carnelian agate (probable)
Cryptocrystalline quartz, SiO₂; chalcedony variety colored by iron oxides
gemstone
Tumbled hematite (likely hematite-rich ironstone)
Hematite, Fe₂O₃; possibly mixed with magnetite or goethite
mineral
Polished rhyolite (likely porphyritic rhyolite)
Rhyolite, composed chiefly of quartz and alkali feldspar with minor plagioclase, biotite, and iron oxides
igneous
Weathered volcanic rock, likely andesite or basalt
Fine-grained mafic to intermediate volcanic rock; probable andesite–basalt, compositionally dominated by plagioclase with pyroxene and possibly alteration minerals
igneous
Quartz geode / iron-stained quartz vein rock
Quartz (SiO₂), likely with iron oxides and minor feldspar or host-rock minerals
mineral
Greenstone / altered basalt fragment
Likely chlorite–epidote–actinolite altered basalt; exact identification requires testing
igneous
Rounded brown pebble, likely chert or iron-stained quartzite
Chert (microcrystalline quartz, SiO₂) or quartzite (recrystallized quartz, SiO₂)
sedimentary
Granite
Phaneritic Igneous Rock
igneous
Diamond and Sapphire
Carbon (Diamond, C) and Aluminum Oxide (Sapphire, Al2O3)
gemstone
Yellow Jade (Quartzite Jade)
Quartzite (SiO2)
gemstone
Banded Gneiss
Gneiss
metamorphic
Leopard Skin Jasper
Silicon Dioxide (SiO2) - Microcrystalline Quartz
sedimentary
Diamond
Native Carbon (C)
gemstone
Chert (Flint)
Microcrystalline Quartz (SiO2)
sedimentary
Chert (Flint Nodules)
Silicon dioxide (SiO2)
sedimentary
Chert / Flint
Silicon dioxide (SiO2)
sedimentary
Chert Pebble
Microcrystalline Quartz (SiO2)
sedimentary
Sandstone
Arenite (SiO2 principal)
sedimentary