Mineral, Part Of A Rock

Polished black stone, possibly basalt or black obsidian

Likely fine-grained basalt (plagioclase and pyroxene) or volcanic glass (obsidian; rhyolitic composition)

Granite Boulder

Felsic Intrusive Igneous Rock

Quartz with Feldspar

Silicon Dioxide (SiO2) with Potassium Feldspar (KAlSi3O8)

Granite

Phaneritic plutonic rock (Quartz, Feldspar, Mica)

Granite Gneiss

Gneiss (High-grade Metamorphic Rock)

Granite

Phaneritic Igneous Rock (Granite)

Granite

Intrusive igneous rock (Acidic)

River Rock (Gneiss/Schist mix)

Foliated Metamorphic Rock (Gneiss)

Fossiliferous Limestone

Biogenic Limestone (Calcium Carbonate, CaCO3)

Coarse Sand Grain / Lithic Fragment

Clastic Sediment (Lithic fragment or Quartz/Feldspar grain)

Granite

Granite (Phaneritic Quartz-rich Igneous Rock)

Likely tumbled quartz or feldspar fragment

Quartz (SiO₂) or feldspar-group silicate

Polished purple quartz (likely amethyst)

Amethyst, a purple variety of quartz (SiO₂), possibly with iron-oxide staining or matrix

Gabbro

Gabbro (Mg,Fe)2Si2O6 and CaAl2Si2O8

Pink Granite

Phaneritic intrusive igneous rock (K-feldspar rich)

Biotite (Black Mica)

Biotite [K(Mg,Fe)3(AlSi3O10)(F,OH)2]

Quartz-rich rock, possibly milky quartz

Quartz (silicon dioxide, SiO₂), possibly with feldspar or mica inclusions

Quartz (Vein Quartz)

Silicon Dioxide (SiO2)

Polished granite countertop with fossil shell

Granite; shell likely a fossilized bivalve or gastropod

Granite

Intrusive Igneous Rock

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Iron-stained milky quartz vein

Quartz (SiO₂), with iron-oxide/hydroxide staining and minor dark inclusions

Quartz Pebble

Silicon Dioxide (SiO2)

Granite Pebble

Felsic Intrusive Igneous Rock (composed of Quartz, Alkali Feldspar, and Plagioclase)

Granite

Intrusive Igneous Rock

Peridotite (Olivine/Peridot)

Peridotite (comprising (Mg,Fe)2SiO4)

Granite

Granite (Phaneritic igneous rock composed primarily of Quartz and Feldspar)

Likely iron-stained quartz or feldspar fragment

Quartz (SiO₂) or potassium feldspar (KAlSi₃O₈), uncertain from image

Painted Garden Rock

Coated Siltstone or Mudstone

Tumbled granitoid pebble, likely granite

Granite: chiefly quartz, potassium feldspar, plagioclase, and dark biotite or amphibole

Biotite (Mica)

Biotite group (K(Mg,Fe)3AlSi3O10(F,OH)2)

Hag Stone

Perforated Flint or Chert

Granite

Felsic intrusive igneous rock

Granite

Felsic intrusive igneous rock

Granite

Phaneritic plutonic rock (Quartz, Feldspar, Mica)

Seashell Fragment (Aragonite/Calcite)

Calcium Carbonate (CaCO3) - Shell fragment

Weathered porphyritic granite with lichen

Granite; predominantly quartz, feldspar, and mica (approximate composition)

River Stone / Pebble

Clastic Sediment (composed largely of Quartz, Feldspar, and various rock fragments)

Granite Pebble

Granite (plutonic igneous rock)

Gneiss

Gneiss (High-grade Metamorphic Rock)

Granite

Granite (Phaneritic Igneous Rock)

Quartz-rich vein rock, possibly milky quartz with iron-oxide staining

Quartz (SiO₂), likely with limonite/goethite and minor host-rock material