Sedimentary Or Igneous (Secondary Formation)

Prehnite

Prehnite (Ca2Al2Si3O10(OH)2)

Weathered quartz-mica schist

Quartz–muscovite/biotite schist, locally iron-oxide stained

Calcite

Calcium Carbonate (CaCO3)

Likely ironstone or weathered chert with an iron-oxide spot

Silicified sedimentary rock, possibly ferruginous chert (microcrystalline SiO₂ with Fe oxides)

Basalt with Quartz Veining

Basalt (Mafic Extrusive Igneous Rock) with SiO2 (Silicon Dioxide) veins

Chert on Volcanic Host Rock

Sedimentary Chert (SiO2) within Basalt or Andesite

Citrine Quartz Geode

Silicon Dioxide (SiO2) with iron impurities

Quartz

Silicon Dioxide (SiO2)

Chert (with Quartz Vein)

Chert (Siliceous sedimentary rock, predominantly Microcrystalline Quartz SiO2)

Quartz

Silicon Dioxide (SiO2)

Basalt with Amygdule

Aphanitic Mafic Volcanic Rock (Basalt) with Zeolite/Quartz Infill

Likely garnet-bearing metamorphic rock

Garnet amphibolite or garnet-bearing schist; chiefly almandine garnet (Fe₃Al₂Si₃O₁₂) with amphibole, mica, and quartz

Okenite

Okenite, Ca3Si6O15·6H2O

Orange Calcite

Calcium Carbonate (CaCO3)

Quartz (Iron-stained)

Silicon Dioxide (SiO2)

Green Calcite

Calcium Carbonate (CaCO3)

Quartz (Citrine or Smoky variety)

Silicon Dioxide (SiO2)

Chert (Jasper / Flint variant)

Microcrystalline Quartz (SiO2)

Likely mica schist

Mica-rich schist, probably biotite–quartz–feldspar schist

Vesicular basalt with secondary mineralization

Mafic volcanic rock, chiefly plagioclase and pyroxene, with iron oxides and likely zeolite/calcite infillings

Quartz vein in host rock

Quartz (SiO₂), likely milky quartz; host rock is uncertain from the photo

Fluorite

Calcium Fluoride (CaF2)

Weathered quartz-rich metamorphic rock, likely gneiss or schist

Quartz–feldspar–mica gneiss/schist (tentative; image resolution limits certainty)

Milky Quartz

Silicon Dioxide (SiO2)

Magnetite (Lodestone variety)

Magnetite (Fe3O4)

Limonite (Iron Ore/Hydrated Iron Oxide)

Limonite (mixture of FeO(OH)·nH₂O minerals, mainly Goethite, FeO(OH) and Lepidocrocite, FeO(OH))

Sandstone with Liesegang Rings

Arenite with secondary Iron oxide (Limonite/Goethite) precipitation

Banded gneiss

Quartz–feldspar gneiss, possibly biotite-bearing; exact identification requires testing

Vesicular basalt with secondary zeolite/mineral crusts

Basalt, chiefly plagioclase–pyroxene ± olivine; cavities partly filled by zeolites or calcite

Small pale mineral/rock fragment

Indeterminate; possibly weathered quartz, calcite, or light-colored limestone

Weathered quartz-bearing metamorphic rock, likely gneiss or quartzite

Quartz-rich gneiss/quartzite with feldspar, mica, and iron-oxide alteration

Geode with Iron-Stained Quartz/Calcite

Silicon Dioxide (SiO2) or Calcium Carbonate (CaCO3) in Sedimentary Matrix

Quartzite with Quartz Vein

Quartzite (SiO2)

Likely quartz fragment

Quartz (silicon dioxide, SiO₂)

Likely garnet-bearing schist or gneiss

Mica schist/gneiss containing quartz, feldspar, mica, and probable almandine garnet

Tourmaline-rich schist (likely black tourmaline)

Schist containing schorl, Fe-rich NaFe3Al6(BO3)3Si6O18(OH)4

Chert (Jasper / Petrified Wood)

Microcrystalline Quartz (SiO2)

Magnetite

Magnetite (Fe3O4)

Magnetite / Iron Ore

Magnetite (Fe3O4)

Quartz crystal cluster

Quartz, silicon dioxide (SiO₂), likely milky or partially included rock crystal

Fluorite

Calcium Fluoride (CaF2)

Likely white quartz or quartz-rich pebble

Quartz (silicon dioxide, SiO₂), possibly a small polished/tumbled specimen