Igneous And Metamorphic Derivative (Weathered)

Quartz (Milky or Smoky Quartz)

Silicon Dioxide (SiO2)

Likely dark mineral or rock fragment

Indeterminate from image; possibly a dark silicate mineral such as hornblende, biotite, or basalt

Banded gneiss (likely garnet-biotite or quartz-feldspar gneiss)

Gneiss; predominantly quartz (SiO₂), feldspar, and dark biotite/amphibole

Possible weathered granite or gneiss

Feldspar–quartz–mica rock; exact identification is uncertain from the photograph

Quartz (River Cobble)

Silicon Dioxide (SiO2)

Weathered quartz-bearing rock, likely granite or granitic gneiss

Feldspar–quartz–mica aggregate; probable granite (compositionally, quartz + feldspar + biotite/muscovite)

Small quartz-rich pebble or rock fragment

Quartz (silicon dioxide, SiO₂), possibly with iron-oxide staining or host-rock inclusions

Milky Quartz with Iron Staining

Quartz (SiO2)

Quartz pebble

Quartz (Silicon dioxide, SiO2)

Rounded gray pebble, likely quartz-rich stone

Indeterminate; possibly quartzite or a weathered granitic pebble

Milky quartz pebble

Quartz (silicon dioxide, SiO₂)

White Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

Quartz (Iron-stained)

Silicon Dioxide (SiO2)

Feldspar (Orthoclase/Microcline)

Potassium Feldspar (KAlSi3O8)

Yellow Sapphire (Corundum)

Corundum (Aluminum Oxide, Al2O3)

Yellow Quartz (Citrine Quartz)

Silicon Dioxide (SiO2)

Milky quartz fragment

Quartz, silicon dioxide (SiO₂)

Milky quartz

Quartz (silicon dioxide, SiO₂)

Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

Smoky Quartz (with possible Feldspar inclusions)

Silicon Dioxide (SiO2)

Likely weathered quartz-bearing rock fragment

Indeterminate; possibly granitic or metamorphic quartz–feldspar aggregate

Quartz pebble

Silicon dioxide (SiO2)

Foliated metamorphic rock, likely gneiss or mica schist

Quartz–feldspar–mica metamorphic rock; exact identification is uncertain from the photograph

Quartz Vein Rock

Silicon Dioxide (SiO2)

Small rough mineral specimen, likely quartz-bearing stone

Indeterminate from image; possibly quartz (SiO₂) with iron-oxide staining

Banded gneiss

Gneiss, likely quartz–feldspar–mica gneiss

Iron-stained quartz rock

Quartz (SiO₂), likely ferruginous quartz or quartz-rich breccia

Milky Quartz with Iron Oxide Weathering

Silicon Dioxide (SiO2) with Goethite/Limonite coatings

Weathered, rounded rock (likely metamorphic or igneous)

Undetermined; possibly a quartz- and feldspar-bearing rock

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

Probable quartz–feldspar aggregate; exact identification requires testing

Rounded quartz-rich pebble, likely milky quartz with iron-oxide inclusions

Quartz (SiO₂), possibly with minor chlorite or iron/manganese oxides

Quartz fragment

Quartz (silicon dioxide, SiO₂)

Mica Sand / Vermiculite

Phyllosilicate group (typically Biotite or Muscovite)

Rounded quartz pebble

Quartz (SiO₂), possibly milky or smoky quartz

River Pebble Quartzite / Granite Cobble

Quartz-rich Granitic / Quartzite Cobble

Weathered quartz-rich rock fragment

Likely quartz-bearing feldspathic rock; exact identification requires testing

Quartz Pebble (often referred to as 'Sea Glass' or 'River Stone' when worn smooth)

Silicon Dioxide (SiO2)

Quartz Pebble

Crystalline Silicon Dioxide (SiO2)

Yellow chalcedony or quartz fragment

Microcrystalline quartz, SiO₂ (tentative; possibly iron-stained chalcedony)

Dark rounded pebble

Likely basalt or another fine-grained mafic volcanic rock; exact identification is uncertain from the image

Quartz (Vein Quartz)

Silicon Dioxide (SiO2)

Milky quartz in weathered host rock

Quartz, SiO₂; likely a quartz vein in altered country rock