Not A Rock

Coquina / Fossiliferous Limestone

Fossiliferous Limestone (CaCO3)

Milky Quartz

Quartz (Silica / Silicon Dioxide), SiO2

Fossiliferous Limestone (Coquina)

Biogenic Limestone (Calcium Carbonate, CaCO3)

Granite

Granite; chiefly quartz, feldspar, and mica

Granite boulder

Granite; chiefly quartz, feldspar, and mica

Gneiss, likely migmatitic or granitic gneiss

Banded quartz–feldspar–mica gneiss; composition chiefly quartz, alkali/plagioclase feldspar, biotite and accessory minerals

Polished banded gneiss

Biotite–quartz–feldspar gneiss, locally migmatitic

Weathered granite fragment

Granite, primarily quartz, feldspar, and mica

Quartz Vein in Basalt or Slate

Hydrothermal quartz vein traversing mafic host rock

Quartz (Druzy)

Silicon Dioxide (SiO2)

Serpentine (likely greenstone)

Serpentine-group minerals, chiefly antigorite, lizardite, and chrysotile; commonly with magnesite or magnetite

Gray rock (possibly basalt or fine-grained granite)

Undetermined; no diagnostic minerals are visible

Gold (Elemental Metal)

Gold (Au)

Iron-stained rock fragment, possibly quartz-rich

Unidentified quartz-rich rock with iron-oxide staining (likely hematite/goethite)

Quartz vein in dark host rock

Quartz (SiO₂), likely in basalt, gabbro, or altered mafic rock

Shale

Shale (claystone/mudstone)

Greenstone (likely chlorite- or epidote-rich metamorphic rock)

Greenstone; commonly metamorphosed basalt or dolerite, with chlorite, epidote, and actinolite

Serpentinite (often called Jade or Nephrite substitute)

Serpentinite (composed primarily of Antigorite, Lizardite, or Chrysotile)

Gneiss

Gneiss (High-grade metamorphic rock)

Quartz Vein in Gneiss or Basalt

Milky Quartz (SiO2) within Metamorphic Host Rock

Red sandstone

Ferruginous quartz arenite (iron-oxide–cemented sandstone)

Dark-colored Igneous Rock (likely Basalt or Diabase)

Basalt (extrusive igneous) or Diabase (intrusive igneous)

Basalt with Quartz/Calcite Veins

Basalt with hydrothermal vein infill

Rounded greenstone pebble

Likely serpentinite or chlorite-rich metamorphic rock; exact identification requires testing

Chalcedony (Agate/Chert variety)

Silicon Dioxide (SiO2)

Quartz (Smoky/Granular variety)

Silicon Dioxide (SiO2)

Moonstone

Orthoclase (Potassium Aluminum Silicate), Formula: (K,Na)AlSi3O8

Weathered granite (likely)

Granite, a quartz–feldspar–mica intrusive igneous rock

Weathered granitic or gneissic cobble

Likely altered granite/granodiorite; exact identification requires a fresh surface and testing

Quartz-Veined Gneiss or Metamorphic Rock with Quartz Veins

Quartz-veined metamorphic rock (Silicate mineral assemblage)

Mixed tumbled river pebbles and beach stones

Polymictic alluvial gravel; components include quartz, chert, jasper, sandstone, and altered volcanic rocks

Mixed rough mineral specimens, likely quartz-bearing rocks

Probable quartz (SiO₂), with possible feldspar, iron oxides, and altered host rock

Red jasper

Jasper, an opaque microcrystalline quartz variety (SiO₂), colored mainly by iron oxides

Shale

Laminated Fissile Pelite

Dalmatian Stone

Peralkaline Quartz-Feldspar Porphyry with Arfvedsonite

Serpentine-rich greenstone

Serpentinite, dominated by serpentine-group minerals (antigorite/lizardite/chrysotile), with possible chlorite, magnetite, and talc

Granite fragment

Granite, chiefly quartz (SiO₂), feldspar, and mica

Rounded gray pebble, likely basalt or andesite

Fine-grained mafic to intermediate volcanic rock; commonly basalt (plagioclase ± pyroxene/olivine)

Brecciated Jasper

Silicon Dioxide (SiO2) with iron oxide inclusions

Granodiorite with Quartz Veining

Granodiorite (containing Plagioclase Feldspar, Quartz, and Biotite/Hornblende) with Quartz (SiO2) veins

Basalt

Basalt

Quartz Geode

Silicon Dioxide (SiO2)