Organic (Pseudo Geological)

Browse organic (pseudo geological) specimens identified by the Rock Identifier community.

Limonite Pseudomorph after Pyrite

Goethite/Limonite FeO(OH)·nH2O replacing Pyrite FeS2

mineral

Limonite (Yellow Ochre)

Limonite (an amorphous mixture of hydrated iron oxides, primarily FeO(OH)·nH2O)

mineral

Muscovite Mica

Muscovite (Potassium Aluminum Silicate Hydroxide Fluoride), KAl2(AlSi3O10)(OH,F)2

mineral

Limonite (also known as Yellow Ochre or Brown Hematite)

Limonite (Hydrated iron oxide-hydroxide, FeO(OH)·nH2O)

Mineral

Tiger's Eye

Silicon dioxide (SiO2) with fibrous inclusions of crocidolite (riebeckite)

Mineral

Polished tiger’s-eye

Quartz variety with fibrous crocidolite pseudomorphs; mainly SiO₂

metamorphic

Goethite

Goethite (α-FeO(OH))

Mineral

Azurite and Malachite on Matrix

Azurite: Cu3(CO3)2(OH)2; Malachite: Cu2CO3(OH)2

mineral

Biotite Mica

K(Mg,Fe)3AlSi3O10(OH)2

Mineral in a matrix (likely quartz or feldspar)

Tiger's Eye (commonly referred to as Blue/Gold Tiger's Eye)

Tiger's Eye is a variety of Chalcedony (cryptocrystalline quartz), SiO2, exhibiting chatoyancy. The blue variety is often called Hawk's Eye.

Metamorphic Rock (formed from a fibrous crocidolite asbestos)

Tumbled tiger’s-eye

Quartz variety, mainly fibrous chalcedony with crocidolite pseudomorphs; SiO₂

metamorphic

Limonite

Hydrous Iron Oxide (often Goethite FeO(OH), Lepidocrocite γ-FeO(OH), and other amorphous iron oxyhydroxides)

Mineral

Tumbled tiger’s eye

Tiger’s eye (chatoyant quartz), SiO₂, typically pseudomorphic quartz after crocidolite

mineral

Goldstone (with Tiger's Eye and Quartz)

Aventurine glass (Synthetic SiO2 with Cu inclusions)

mineral

Conglomerate

Conglomerate (a clastic sedimentary rock)

Sedimentary

Tiger's Eye

Silicon dioxide (SiO2) with fibrous inclusions of crocidolite (riebeckite) that have been altered to limonite and then replaced by quartz

Mineral

Blue Tiger's Eye

Crocidolite in Quartz (altered)

Mineral

Tiger's Eye

Tiger's Eye (a variety of Chalcedony, which is cryptocrystalline quartz). Chemical Formula: SiO2 with inclusions of crocidolite fibers.

Mineral

Tiger's Eye

Tiger's Eye (a variety of Quartz, SiO₂)

Mineral (specifically a gemstone variety)

Sandstone with trace fossil

Sandstone, possibly with Skolithos or similar trace fossil

sedimentary

Hawk's Eye (Blue Tiger's Eye)

Quartz (fibrous crocidolite variety)

Mineral

Blue Tiger's Eye

Crocidolite (fibrous riebeckite) silicified to Quartz (SiO2)

Mineral

Blue Tiger's Eye

Riebeckite (crocidolite variety)

Mineral

Tiger’s eye beads

Tiger’s eye (quartz variety), SiO₂, with pseudomorphic fibrous crocidolite/goethite inclusions

mineral

Tiger’s-eye bead bracelet

Chatoyant quartz, principally quartz (SiO₂) with pseudomorphic fibrous crocidolite/goethite inclusions

gemstone

Tiger's Eye

Tiger's Eye (a variety of Chalcedony, which is a microcrystalline quartz with fibrous inclusions of oxidized crocidolite)

Mineral

Mica Group Minerals

There isn't a single scientific name as 'Mica' refers to a group of phyllosilicate minerals. Common scientific names include Muscovite (KAl₂ (AlSi₃O₁₀)(OH)₂), Biotite (K(Mg,Fe)₃AlSi₃O₁₀(OH)₂), Phlogopite (KMg₃AlSi₃O₁₀(OH)₂), and Lepidolite (K(Li,Al)₃(Al,Si,Rb)₄O₁₀(F,OH)₂).

Mineral