Mineral In Igneous Rock

Small tumbled pebble (likely quartz or feldspar)

Indeterminate; probable quartz (SiO₂) or feldspar

Granite

Felsic intrusive igneous rock

Black Obsidian

Volcanic Glass (Amorphous SiO2 with trace impurities)

Granite

Granite (Felsic Plutonic Rock)

Blue-gray quartz-rich rock, possibly blue aventurine or sodalite-bearing stone

Probable quartz–feldspar aggregate; exact identification requires testing

Iron-rich breccia or weathered ironstone

Goethite–hematite-bearing limonite, possibly with quartz and altered rock fragments

Granite Pebble

Intrusive igneous rock (Quartz, Feldspar, Mica)

Diorite (River Pebble)

Intermediate Phaneritic Igneous Rock

Basalt Pebble

Extrusive Igneous Rock

Pink Granite (Unakite-bearing or Epidote-bearing Granite)

Plutonic Igneous Rock (Granite)

Magnetite

Magnetite (Fe3O4)

Sodalite with Syenite (Yooperlite)

Sodalite in Syenite (Na8(Al6Si6O24)Cl2)

Granite Gravel (Pebble)

Intrusive Felsic Igneous Rock

Granite

Felsic intrusive igneous rock

Granite

Felsic intrusive igneous rock

Granite

Intrusive Igneous Rock

Biotite-bearing granite

Granite, composed chiefly of quartz, feldspar, and biotite; exact identification is uncertain from the photo.

Granite

Granite, a felsic intrusive igneous rock composed chiefly of quartz, feldspar, and mica

Gneiss

Gneiss (Metamorphic Rock)

Basalt Pebble

Extrusive Igneous Rock (Mafic)

Peridotite

Ultramafic igneous rock

Granite Pebble

Granite (Plutonic Igneous Rock)

Granite

Felsic intrusive igneous rock

Granite Pebble

Intrusive Igneous Rock (Granite)

Diorite

Phaneritic Intermediate Igneous Rock

Peach Moonstone

Potassium Aluminum Silicate (KAlSi3O8)

Granite

Intrusive igneous felsic rock

Granite

Phaneritic felsic intrusive igneous rock

Quartz (Iron-stained Quartz)

Silicon Dioxide (SiO2)

Orbicular granite (likely rapakivi-type granite)

Granite; chiefly quartz, alkali feldspar, plagioclase, and biotite/hornblende

Granite

Granite (Plutonic Igneous Rock)

Weathered granite (likely)

Granite, a quartz–feldspar–mica intrusive igneous rock

Possible iron-rich pebble with a weathered inclusion

Unidentified; image alone does not support a reliable mineral or rock identification

Granite Pebble

Phaneritic intrusive igneous rock

Milky Quartz in Epidote Host Rock

Crystalline Silicon Dioxide (SiO2) with Epidote Ca2(Al,Fe)3(SiO4)3(OH)

Smooth gray pebbles

Unidentified rounded rock fragments; composition cannot be determined from the image

Small dark mineral or rock fragment

Undetermined; possibly a dark mafic mineral such as biotite or magnetite

Granite

Felsic intrusive igneous rock

Vesicular Basalt (Lava Rock)

Vesicular Basalt

Granite

Phaneritic Igneous Rock (Granite)

Red granite (likely weathered granite or granitic gneiss)

Granite; chiefly quartz (SiO₂), feldspar, and mica, with iron-oxide staining

Granite / Feldspar gravel

Granite (felsic intrusive igneous rock)