Rock Identifier

Category

Mineraloid (Cryptocrystalline Quartz)

Browse mineraloid (cryptocrystalline quartz) specimens identified by the Rock Identifier community.

Learn about Mineraloid (Cryptocrystalline Quartz) in the encyclopedia

Chalcedony

Black Onyx

Landscape Agate

Landscape Agate

Tube Agate

Sweetwater Agate

Sweetwater Agate

Frost Agate

Coldwater Agate

Honey Agate

Zebra Agate

Flame Agate

Feather Agate

Cathedral Agate

Cathedral Agate

Red Jasper (Jasper (a variety of Chalcedony, SiO₂)) — Mineraloid (cryptocrystalline quartz)

Red Jasper

Jasper (a variety of Chalcedony, SiO₂)

Mineraloid (cryptocrystalline quartz)

Limonite or Ironstone Nodule (FeO(OH)·nH2O (Hydrated iron(III) oxide-hydroxide)) — sedimentary

Limonite or Ironstone Nodule

FeO(OH)·nH2O (Hydrated iron(III) oxide-hydroxide)

Obsidian (Volcanic glass (mainly SiO2 with inclusions)) — igneous

Obsidian

Volcanic glass (mainly SiO2 with inclusions)

Snowflake Obsidian (Spherulitic Volcanic Glass (primarily SiO2 with Cristobalite inclusions)) — igneous

Snowflake Obsidian

Spherulitic Volcanic Glass (primarily SiO2 with Cristobalite inclusions)

Snowflake Obsidian (Spherulitic Volcanic Glass (primarily SiO2)) — igneous

Snowflake Obsidian

Spherulitic Volcanic Glass (primarily SiO2)

Limonite/Goethite on Shale (Hydrous ferric oxides (FeO(OH)·nH2O) often associated with argillaceous rock) — sedimentary

Limonite/Goethite on Shale

Hydrous ferric oxides (FeO(OH)·nH2O) often associated with argillaceous rock

Snowflake Obsidian (Flower Jasper variant) (Vitreous volcanic silicate with cristobalite inclusions) — igneous

Snowflake Obsidian (Flower Jasper variant)

Vitreous volcanic silicate with cristobalite inclusions

Limonite (Iron Ore) (Hydrous ferric oxides (FeO(OH)·nH2O)) — mineral

Limonite (Iron Ore)

Hydrous ferric oxides (FeO(OH)·nH2O)

Common Opal (SiO2·nH2O (Hydrated Silicon Dioxide)) — mineraloid

Common Opal

SiO2·nH2O (Hydrated Silicon Dioxide)

Cullet Glass (Slag) (Amorphous Silicon Dioxide (Man-made)) — Mineraloid

Cullet Glass (Slag)

Amorphous Silicon Dioxide (Man-made)

Common Opal in Host Rock (Hydrated Silica (SiO2·nH2O)) — mineraloid

Common Opal in Host Rock

Hydrated Silica (SiO2·nH2O)

Green Opal or Yellow Opal (Hydrated Silica (SiO2·nH2O)) — mineraloid

Green Opal or Yellow Opal

Hydrated Silica (SiO2·nH2O)

Limonite (Ironstone) Concretion (FeO(OH)·nH2O (Hydrous ferric oxide)) — sedimentary

Limonite (Ironstone) Concretion

FeO(OH)·nH2O (Hydrous ferric oxide)

Snowflake Obsidian (Volcanic Glass with Cristobalite inclusions (70–75% SiO2)) — Igneous

Snowflake Obsidian

Volcanic Glass with Cristobalite inclusions (70–75% SiO2)

Snowflake Obsidian (Spherulitic Obsidian (primarily SiO2 with Cristobalite inclusions)) — igneous

Snowflake Obsidian

Spherulitic Obsidian (primarily SiO2 with Cristobalite inclusions)

Ethiopian Opal (Welo Opal) (Hydrated Amorphous Silica (SiO2·nH2O)) — mineraloid

Ethiopian Opal (Welo Opal)

Hydrated Amorphous Silica (SiO2·nH2O)

Opal (Hydrated Amorphous Silica (SiO2·nH2O)) — mineral

Opal

Hydrated Amorphous Silica (SiO2·nH2O)

Pink Opal (Hydrated Amorphous Silica (SiO2·nH2O)) — mineraloid

Pink Opal

Hydrated Amorphous Silica (SiO2·nH2O)

Pink Opal (Hydrated Silicon Dioxide (SiO2 · nH2O)) — mineraloid

Pink Opal

Hydrated Silicon Dioxide (SiO2 · nH2O)

Precious Opal (Hydrated silica (SiO2·nH2O)) — mineraloid

Precious Opal

Hydrated silica (SiO2·nH2O)

Tumbled mahogany obsidian (Volcanic glass; primarily SiO₂ with iron-oxide-rich brown inclusions) — igneous

Tumbled mahogany obsidian

Volcanic glass; primarily SiO₂ with iron-oxide-rich brown inclusions

Green Opal (Hydrated Silica (SiO2·nH2O)) — mineraloid

Green Opal

Hydrated Silica (SiO2·nH2O)

Black Opal (Triplet) (Hydrated Silica (SiO2·nH2O)) — mineral

Black Opal (Triplet)

Hydrated Silica (SiO2·nH2O)

Black Obsidian (Obsidian (Volcanic Glass)) — igneous

Black Obsidian

Obsidian (Volcanic Glass)

Snowflake Obsidian (Volcanic Glass with Spherulite Inclusions (primarily SiO2)) — igneous

Snowflake Obsidian

Volcanic Glass with Spherulite Inclusions (primarily SiO2)

Amber (Succinite (a specific common type) or Fossilized Tree Resin (C10H16O)) — Mineraloid

Amber

Succinite (a specific common type) or Fossilized Tree Resin (C10H16O)

Limonite and Goethite (Ironstone) (Hydrous Iron Oxide Mixture (FeO(OH)·nH2O)) — sedimentary

Limonite and Goethite (Ironstone)

Hydrous Iron Oxide Mixture (FeO(OH)·nH2O)

Sea Glass (Frosted Quartz/Glass) (Amorphous Silicon Dioxide (SiO2)) — Mineraloid

Sea Glass (Frosted Quartz/Glass)

Amorphous Silicon Dioxide (SiO2)

Snowflake Obsidian (Spherulitic Volcanic Glass (SiO2 + impurities)) — igneous

Snowflake Obsidian

Spherulitic Volcanic Glass (SiO2 + impurities)

Snowflake Obsidian (Volcanic glass with Cristobalite inclusions (mostly SiO2)) — igneous

Snowflake Obsidian

Volcanic glass with Cristobalite inclusions (mostly SiO2)

Snowflake Obsidian (Volcanic glass (SiO2 - Silicon Dioxide with Cristobalite inclusions)) — igneous

Snowflake Obsidian

Volcanic glass (SiO2 - Silicon Dioxide with Cristobalite inclusions)

Limonite with Quartz (Gossan) (Hydrated iron(III) oxide-hydroxide mixture (FeO(OH)·nH2O) with Silicon Dioxide (SiO2)) — Mineral

Limonite with Quartz (Gossan)

Hydrated iron(III) oxide-hydroxide mixture (FeO(OH)·nH2O) with Silicon Dioxide (SiO2)

Limonite (Iron Ore) (Limonite (an FeO(OH)·nH2O mineraloid, not a true mineral due to variable composition)) — Mineral

Limonite (Iron Ore)

Limonite (an FeO(OH)·nH2O mineraloid, not a true mineral due to variable composition)

Mahogany Obsidian (Volcanic glass (SiO2 + Fe2O3)) — igneous

Mahogany Obsidian

Volcanic glass (SiO2 + Fe2O3)

Precious Opal (Hydrated Silicon Dioxide (SiO2·nH2O)) — gemstone

Precious Opal

Hydrated Silicon Dioxide (SiO2·nH2O)

White Opal (Common) (Hydrated Silica (SiO2·nH2O)) — mineral

White Opal (Common)

Hydrated Silica (SiO2·nH2O)

Chalcedony (or a variety of Chalcedony, likely Agate or Jasper) (Chalcedony (SiO₂)) — Mineral (or mineraloid if microcrystalline)

Chalcedony (or a variety of Chalcedony, likely Agate or Jasper)

Chalcedony (SiO₂)

Mineral (or mineraloid if microcrystalline)

Black Obsidian (Volcanic Glass (predominantly SiO2, Silicon Dioxide)) — igneous

Black Obsidian

Volcanic Glass (predominantly SiO2, Silicon Dioxide)

Common Opal (Potch) (Hydrated Silica (SiO2·nH2O)) — mineral

Common Opal (Potch)

Hydrated Silica (SiO2·nH2O)

Chalcedony Bangle (SiO2) — gemstone

Chalcedony Bangle

SiO2

Red Sandstone (Clastic Sedimentary Mineraloid (predominantly Quartz grains with Iron Oxide cement)) — sedimentary

Red Sandstone

Clastic Sedimentary Mineraloid (predominantly Quartz grains with Iron Oxide cement)

Chalcedony (Quartz Pebbles) (Silicon Dioxide (SiO2)) — mineral

Chalcedony (Quartz Pebbles)

Silicon Dioxide (SiO2)