Carnelian
Chalcedony (SiO2)
mineral
Category
Mineraloid (Cryptocrystalline Quartz)
Browse mineraloid (cryptocrystalline quartz) specimens identified by the Rock Identifier community.
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Agate and Chalcedony Assortment
Silicon Dioxide (SiO2)
mineral
Chert (Flint)
Cryptocrystalline Silica (SiO2)
sedimentary
Tumbled red jasper with a quartz vein
Jasper (microcrystalline quartz, SiO₂), likely crossed by milky quartz
metamorphic
Tumbled milky quartz
Quartz (SiO₂), cryptocrystalline to coarse-grained quartz aggregate
mineral
Carnelian Agate
Silicon Dioxide (SiO2)
mineral
Red Chalcedony (likely dyed)
Chalcedony (a variety of Quartz), SiO2
Mineral (Cryptocrystalline Quartz)
Chalcedony and Malachite
SiO2 (Chalcedony) and Cu2CO3(OH)2 (Malachite)
gemstone
Petrified Wood
Agatized or Silicified Wood (SiO2)
fossil
Agate
Chalcedony (SiO2)
mineral
Chert (Flint/Jasper variety)
Silicon Dioxide (SiO2)
sedimentary
Jasper / Agate with Petrified Wood Inclusion
SiO2
mineral
Tumbled quartz-rich pebble
Microcrystalline quartz/chalcedony, SiO₂ (tentative)
mineral
Agate
SiO2
Mineral
Blue Chalcedony (Moonstone-like / Agate)
Silicon Dioxide (SiO2) - Microcrystalline Quartz
gemstone
Carnelian
Carnelian (Chalcedony/Quartz, SiO2)
mineral
Massive Cryptocrystalline Quartz (Chert/Chalcedony Pebble)
Silicon Dioxide (SiO2)
sedimentary
Polished blue-green agate slice
Agate, a banded microcrystalline variety of chalcedony (SiO₂), commonly colored by trace minerals
mineral
Tumbled yellow chalcedony (likely honey quartz or pale citrine)
Microcrystalline quartz, SiO₂; exact identity cannot be confirmed visually
mineral
Mixed Tumbled Rocks and Minerals Collection
Mixed Minerals and Rocks (Quartz, Feldspar, Jasper, Agate, Lapis Lazuli, Sodalite, Rose Quartz, Fluorite, etc.)
mineral
Tumbled quartz or chalcedony (uncertain)
Quartz, SiO₂; possibly cryptocrystalline chalcedony
mineral
Geode
Quartz / Chalcedony nodule
sedimentary
Chrysocolla in Quartz
Hydrated copper phyllosilicate with silicon dioxide (Cu2-xAlx(H2-xSi2O5)(OH)4·nH2O + SiO2)
mineral
Engineer Quartz/Quartzite
SiO2 (Silicon Dioxide with binders)
Sedimentary or metamorphic-derived
Tumbled agate or chalcedony nodule
Microcrystalline quartz (SiO₂), likely agate/chalcedony with iron-oxide staining
mineral
Quartz Vein in Basalt or Porphyry
Silicate-veined volcanic rock
igneous
Orbicular jasper / brecciated jasper
Silica-rich microcrystalline quartz (chalcedony), commonly with iron oxides and altered volcanic fragments
metamorphic
Yellow chert or jasper pebble
Microcrystalline quartz (SiO₂), likely iron-oxide-stained chert/jasper
sedimentary
Chert / Flint (Artifact)
Microcrystalline quartz (SiO2)
sedimentary
Chert (specifically Flint or Common Opal fragment)
Cryptocrystalline Silica (SiO2)
sedimentary
Chalcedony (possibly lavender or gray agate)
Microcrystalline quartz, SiO₂; fibrous quartz aggregate
mineral
Petrified Wood
Silicified Wood (SiO2)
fossil
Tumbled quartz
Quartz (silicon dioxide, SiO₂), likely milky or included quartz
mineral
Chert / Flint (Artifact)
Microcrystalline Quartz (SiO2)
sedimentary
Shiva Lingam
Cryptocrystalline Quartz (Jasproid/Chalcedony mix)
sedimentary
Milky quartz (possibly chalcedony)
Quartz, SiO₂; likely massive or cryptocrystalline quartz
mineral
Chalcedony in Limestone Host Rock
Silicon Dioxide (SiO2) within Calcium Carbonate (CaCO3)
Mineral within Sedimentary Rock
Dyed Chalcedony (Agate)
Silicon Dioxide (SiO2) with artificial pigment
mineral
Quartz Pebble (Chalcedony / River Pebble)
Silicon Dioxide (SiO2)
mineral
Jasper and Chalcedony Pebble
Silicon Dioxide (SiO2)
sedimentary
Flint / Chert (Hag Stone)
Silicon Dioxide (SiO2)
sedimentary
Orange Quartzite (or Yellow Jasper / Carnelian Chalcedony)
Silicon Dioxide (SiO2)
metamorphic