Mineral, Specifically A Rock Fragment

Quartz (Citrine or Iron-Stained variety)

Silicon Dioxide (SiO2)

Green Aventurine

Aventurine Quartz (SiO2 with inclusions)

Epidosite (Unakite-related)

Epidosite (composed primarily of Epidote and Quartz)

Carnelian

Carnelian Chalcedony (SiO2 with Iron Oxide impurities)

Flower Agate (Plume Agate)

Chalcedony (Silicon Dioxide) with Spherulitic Inclusions - SiO2

African Turquoise

Jasper / Quartz matrix (Trade name: African Turquoise, chemically a form of microcrystalline quartz with various mineral inclusions)

Granite or granitic rock fragment

Felsic intrusive igneous rock, typically quartz + feldspar + mica; exact species uncertain from the image

Jasper (specifically Red or Brecciated Jasper variant)

Jasper (Microcrystalline Quartz - SiO2)

Green Calcite

Calcium Carbonate (CaCO3)

Dalmatian Jasper

Peralkaline Quartz-Feldspar Rock with Arfvedsonite

Fossiliferous Shale

Laminated Mudrock with plant fossils

Smoky Quartz

Silicon Dioxide (SiO2)

Fossiliferous Shale

Fossiliferous Mudstone / Shale

Blue Lace Agate (Tumbled)

Silicon Dioxide (SiO2) with trace minerals

Dendritic Agate

Silicon Dioxide (SiO2) with Manganese/Iron inclusions

Marble

Recrystallized Calcite (CaCO3) or Dolomite (CaMg(CO3)2)

Clear Quartz (Druzy)

Crystalline Silicon Dioxide (SiO2)

Weathered granite-like rock

Granite, likely biotite-bearing; exact identification is uncertain from the image

Agate in Rhyolite

Silicon Dioxide (Quartz/Chalcedony) in Volcanic Rock matrix

Weathered sandstone or granitic rock fragment

Likely quartz-rich sandstone; exact identification requires testing

Sandstone

Arenite (specifically sublithic or quartz arenite)

Basalt Fragment

Extrusive Igneous Rock

Milky Quartz

Silicon Dioxide (SiO2)

Herkimer Diamond

Quartz (Silicon Dioxide, SiO2)

Milky quartz vein fragment

Quartz, silicon dioxide (SiO₂)

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Fossil bivalve shell

Fossilized or partially mineralized bivalve; exact genus cannot be determined from the image

Muscovite Mica

Muscovite / KAl2(AlSi3O10)(OH)2

Quartz Crystal (specifically a Double-Terminated variety)

Silicon Dioxide (SiO2) - Low Quartz

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Weathered volcanic rock fragment

Likely andesite or basalt; exact identification requires fresh surface and testing

Possible flint or slag fragment

Microcrystalline quartz (chalcedony), or iron-rich industrial slag

Pink Granite

Phaneritic Intrusive Igneous Rock (Granite)

Chert

Silicon dioxide (SiO2)

Quartz (Small Fragment)

Silicon Dioxide (SiO2)

Quartz Geode

Crystalline Silicon Dioxide (SiO2)

Unidentified River Rock or Mudstone

N/A (Generic rock fragment)

Red Sandstone

Sedimentary Clastic Rock (Quartz Arenite)

Quartz pebble with host matrix

Silicon Dioxide (SiO2)

Milky Quartz

Quartz (Silicon Dioxide - SiO2)

Weathered granite (likely biotite granite)

Granite; interlocking quartz, feldspar, and mica, commonly with biotite