Sedimentary Rock (Altered)

Browse sedimentary rock (altered) specimens identified by the Rock Identifier community.

Lapis Lazuli (blue bead) and Moss Agate (green heart)

Lapis Lazuli (lazurite-based rock) and Moss Agate (SiO2 with manganese/iron inclusions)

metamorphic (Lapis) and sedimentary/igneous assoc. (Moss Agate)

Orthoclase Feldspar (or K-Feldspar)

Orthoclase (KAlSi3O8)

Mineral

Chert or Flint (polished/water-worn)

Chert (a microcrystalline or cryptocrystalline variety of quartz, SiO2). Flint is a specific variety of chert.

Sedimentary (most likely, as Chert is a sedimentary rock often found as nodules in limestone or as bedded deposits; however, it can also form by metasomatic replacement, which leans towards metamorphic processes under certain conditions)

Schist

Schist (various mineralogical compositions including mica, chlorite, talc, etc.)

Metamorphic

Jasper (likely Lake Superior Jasper)

Silicon Dioxide (SiO2) with iron oxide inclusions

sedimentary (silica-rich mineral variety)

Quartz

Quartz (SiO₂)

Mineral

Quartz

Silicon Dioxide (SiO2)

Mineral

Gneiss

Gneiss (pronounced 'nice')

Metamorphic Rock

Turritella Agate (Elimia Agate)

Silicified Elimia tenera (formerly misidentified as Turritella)

sedimentary (silicified fossiliferous chalcedony)

Veined Quartz

SiO2 (Silicon Dioxide)

Mineral

Quartz Geode/Druzy Quartz

Quartz (SiO₂)

Mineral

Glauconitic Sandstone (or Greensand)

Glauconitic Siliciclastic Rock (Containing (K,Na)(Fe,Al,Mg)2(Si,Al)4O10(OH)2)

sedimentary

Quartz (variety of colors)

SiO2 (Silicon Dioxide)

Mineral

Quartz (Milky Quartz)

Quartz (SiO2 - Silicon Dioxide)

Mineral

Granite (phaneritic background) with Limestone/Calcite carving

Felsic Igneous Plutonic Rock (background) / Calcium Carbonate (CaCO3) (carving)

igneous and sedimentary

Amber (Cherry or Red variety)

Succinite (with various trace amounts of organic compounds)

Organic Gemstone (not a rock)

Jasper in Basalt Matrix

Silicon Dioxide (SiO2) with impurities; Chalcedony

sedimentary (secondary mineral) within igneous

Banded Gneiss

Gneiss (pronounced "nice")

Metamorphic Rock

Quartz Druzy on Agate (River Cobble)

Silicon Dioxide (SiO2)

Mineral / Sedimentary (often associated with volcanic hosts)

Brecciated Jasper

Silicon Dioxide (SiO2) with varying mineral inclusions (Iron Oxide, Hematite, Clay)

sedimentary (clastic/chemical)

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2)

mineral

Calcite (likely a tumbled specimen)

Calcite (CaCO 3 )

Mineral

Quartz (Crystal/Druzy Quartz)

Quartz (SiO₂)

Mineral

Corundum

Corundum (Al2O3)

Mineral

Asphalt (Bituminous Concrete)

Bituminous mix / Anthropogenic conglomerate

man-made composite (lithified equivalent of sedimentary)

Quartz

Quartz (SiO₂ - Silicon Dioxide)

mineral

Muscovite Mica

Muscovite (KAl2(AlSi3O10)(OH)2)

Mineral

Quartz

Quartz (SiO2)

Mineral

Quartz

Silicon Dioxide (SiO₂)

Mineral

Chert (Jasper Variant likely)

Silicon Dioxide (SiO2)

Sedimentary Rock or Mineral (depending on origin and purity)

River Rock (Basalt/Greywacke pebbles)

Fluvial gravel primarily composed of Mafic Volcanic Rock (Basalt) or Lithic Sandstone (Greywacke)

igneous and sedimentary

Concrete Fragment

Hardened Portland Cement Composite

Anthropogenic (Man-made material mimicking sedimentary rock)

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

Banded Gneiss

Gneiss

Metamorphic

Quartz (River Pebble)

Quartz (SiO₂ - Silicon Dioxide)

Mineral

Green Aventurine and Clear Quartz

Green Aventurine (Silicon Dioxide - SiO2 with Fuchsite inclusions); Clear Quartz (Silicon Dioxide - SiO2)

Mineral

Baltic Amber (Butterscotch or Egg Yolk Variety)

Succinite (chemical formula: C10H16O)

Organic Gemstone (not a rock or mineral)

Chalcedony or Chert/Jasper with secondary mineral staining

SiO2 (for chalcedony/quartz) with possible secondary copper minerals (e.g., CuSiO3·nH2O for chrysocolla, Cu2(CO3)(OH)2 for malachite) or iron oxides/hydroxides.

Mineral, potentially a rock with chalcedony/jasper.