Limonite (Iron Ore/Sandstone mixture)
Limonite (FeO(OH)·nH2O) often mixed with Goethite and sedimentary matrix
mineral
Category
The Purple Specimen Is A Mineral (Amethyst); The White Specimen Is A Sedimentary Rock (Limestone Or Marble).
Browse the purple specimen is a mineral (amethyst); the white specimen is a sedimentary rock (limestone or marble). specimens identified by the Rock Identifier community.
Amethyst (Tumbled Quartz)
Silicon Dioxide (SiO2)
mineral
Quartzite
Quartzite (primarily SiO2)
metamorphic
Orange Calcite (Carved as a Horned Skull)
Calcium Carbonate (CaCO3)
mineral
Banded Agate
Cryptocrystalline variety of Quartz (SiO2)
mineral
Lapis Lazuli
Lapis Lazuli (aggregate of Lazurite, Calcite, and Pyrite)
metamorphic
Moss Agate
Chalcedony (Silicon Dioxide / SiO2)
mineral
Quartz in Matrix (possibly with Biotite or Hornblende)
Quartz (Silicon Dioxide, SiO2) in Granitic Matrix
igneous
Chert (Nodule)
Microcrystalline or Cryptocrystalline Quartz (SiO2)
sedimentary
Chert (Flint)
Chert (SiO2)
sedimentary
Fluorite
Calcium Fluoride (CaF2)
mineral
Sandstone (Quartzose Sandstone Pebble)
Arenite (primarily SiO2)
sedimentary
Sandstone (specifically Arkose or Quartz Arenite)
Arenite (primarily SiO2 with possible Feldspar)
sedimentary
Bivalve Fossil in Sedimentary Matrix
Fossiliferous Mudstone (Class: Bivalvia)
sedimentary
Iridescent Ammonite
Ammonoidea (Species: likely Cleoniceras or Desmoceras); Mineral: Aragonite/Ammolite (CaCO3)
sedimentary (fossilized)
Quartz Crystal (specifically a small Clear Quartz point)
Silicon Dioxide (SiO2)
mineral
Septarian Nodule (Septarian Dragon Stone)
Septarian Concretion (Composition: Calcite, Aragonite, and Limestone/Clay)
sedimentary
Quartz (Milky Quartz/Citrine Type)
Silicon Dioxide (SiO2)
mineral
Quartz Geode
Silicon Dioxide (SiO2)
mineral
Brecciated Chert
Brecciated Chert (Microcrystalline Quartz, SiO2)
sedimentary
Chert / Jasper
Cryptocrystalline Quartz (SiO2)
sedimentary
Red Jasper (in Quartz/Chalcedony)
Silicon Dioxide (SiO2) with iron oxide inclusions
sedimentary
Chert (often called Flint or Jasper)
Silicon Dioxide (SiO2)
sedimentary
Amethyst (Rough Crystal)
Silicon Dioxide (SiO2 with ferric iron impurities)
mineral
Amethyst (Purple), Sulfur (Yellow), and Blue Apatite
SiO2 (Quartz), S (Native Sulfur), Ca5(PO4)3(F,Cl,OH) (Apatite Group)
mineral
Clear Quartz (Rock Crystal)
Silicon Dioxide (SiO2)
mineral
Red Quartzite (River Pebble)
Quartzite (primarily Silicon Dioxide - SiO2)
metamorphic
Gneiss (Metamorphic Rock)
Gneiss (high-grade regional metamorphic rock)
metamorphic
Chert (Tan/Yellow variety)
Microcrystalline Quartz (SiO2)
sedimentary
Clear Quartz
Silicon Dioxide (SiO2)
mineral
Specular Hematite with Quartz and Limonite
Hematite (Fe2O3) with Quartz (SiO2) and Limonite (FeO(OH)·nH2O)
Mineral
Chert / Flint Nodule
Silicon Dioxide (SiO2)
sedimentary
Massive Quartz
Silicon Dioxide (SiO2)
mineral
Sandstone (Ferruginous)
Arenite with Iron Oxide staining (Fe2O3)
sedimentary
Quartz Pebble
Silicon Dioxide (SiO2)
Mineral
Jasper (brecciated or orbicular variety)
Silicon dioxide (SiO2) with iron oxide inclusions
sedimentary/mineral
Sandstone
Clastic Sedimentary Rock (composed mostly of quartz, SiO2)
sedimentary
Chert (Flint variety)
Microcrystalline Silica (SiO2)
sedimentary
Quartz (Quartzite)
Silicon Dioxide (SiO2)
mineral
River Cobble (Gneiss/Migmatite)
Gneissic Metamorphic Rock (composed mainly of Quartz, Feldspar, and Biotite)
metamorphic
Quartz (Smoky/Milky Variety)
Silicon Dioxide (SiO2)
mineral
Sandstone (likely Graywacke or Arkose variant)
Clastic Sedimentary Rock (SiO2 with assorted lithic fragments)
sedimentary