Sedimentary Or Igneous Fragment

Weathered schist or gneiss boulder

Micaceous quartz-feldspar schist/gneiss; exact identification is limited by the photograph

Quartz Drusy (on Geode Fragment)

Crystalline Silicon Dioxide (SiO2)

Silver-colored mica schist

Muscovite–quartz schist, possibly with biotite

Tumbled brecciated jasper

Silica-rich microcrystalline quartz/chalcedony (SiO₂), with iron-oxide and other mineral inclusions

Likely quartz-rich stone, possibly milky quartz or chalcedony

Quartz (SiO₂), possibly microcrystalline chalcedony

Quartz

Silicon Dioxide (SiO2)

Mixed mineral and rock specimen collection

Mixed assemblage, visibly including quartz, chalcedony/agate, feldspar, mica, dark mafic rocks, and possibly calcite or gypsum

Basalt with Chert/Obsidian blade

Aphanitic Mafic Igneous Rock (Basalt) with Microcrystalline Silica (Chert)

Clear quartz fragment

Quartz (silicon dioxide, SiO₂)

Generic Pebble / Rock Fragment

Lithic fragment / Weathered rock

Tumbled quartz crystal

Quartz (silicon dioxide, SiO₂)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Unidentified translucent crystal/mineral fragment

Likely quartz (SiO₂), but visual identification is uncertain

Weathered fossiliferous limestone, likely coral or shell fragment

Calcite (CaCO₃), biogenic limestone; exact fossil taxon indeterminate from the image

Weathered reddish-brown rock fragment

Probably altered basalt or fine-grained volcanic rock; exact identification requires testing

Rounded metamorphic pebble, likely mica schist or gneiss

Mica schist/gneiss; commonly quartz, feldspar, and biotite or muscovite mica

Dark basalt or fine-grained mafic rock

Basalt; primarily plagioclase feldspar, pyroxene, and commonly olivine or iron-titanium oxides

Quartz Geode

Silicon Dioxide (SiO2) within Sedimentary or Igneous host

Quartz (with Sandstone/Quartzite rocks)

Silicon Dioxide (SiO2)

Weathered metamorphic rock, likely mica schist or gneiss

Quartz–feldspar–mica schist/gneiss; exact identification is uncertain from the photograph

Unidentified dark gray rock fragment

Likely fine-grained basalt or andesite; exact identification requires testing

Likely basalt fragment

Basalt, a fine-grained mafic volcanic rock composed mainly of plagioclase feldspar and pyroxene, commonly with olivine

Milky quartz vein fragment

Quartz (silicon dioxide, SiO₂), massive or granular variety

Uncertain—likely weathered granite or quartz-rich rock

Granite (quartz–feldspar–mica aggregate), tentative

Gravel (Crushed Stone Aggregates)

Mixed Siliciclastic / Carbonate Aggregate

Likely foliated metamorphic rock (quartz-mica schist or gneiss)

Quartz–feldspar–mica metamorphic rock; exact identification requires a fresh surface and tests

Garnet-bearing metamorphic rock, likely garnet schist or amphibolite

Almandine garnet (Fe₃Al₂Si₃O₁₂) in mica- or amphibole-rich matrix

Quartz Sand Grain / Micro Crystal

Silicon Dioxide (SiO2)

Gneiss (specifically Banded Gneiss)

Gneiss

Conglomerate

Conglomerate (clastic sedimentary rock)

Clear quartz crystal (likely quartz fragment)

Quartz, silicon dioxide (SiO₂)

Clear quartz crystal

Quartz (silicon dioxide, SiO₂), likely milky or included rock crystal

Gneiss

Gneiss

Quartz (Milky/Smoky Crystal fragment)

Silicon Dioxide (SiO2)

Pebble

Lithic fragment / Sedimentary clast

River Pebble

Weathered Sedimentary Rock Fragment

Waterworn Pebble / Quartzite

Metamorphic/Sedimentary rock fragment

Likely quartz crystal fragment

Quartz (SiO₂), possibly a small tumbled or cleaved fragment

Weathered volcanic rock, likely altered basalt/andesite

Fine-grained mafic to intermediate volcanic rock; possible chlorite–calcite alteration

River Pebble (Gneiss / Granitic Schist)

Metamorphic Rock (Quartz-Feldspar-Mica assembly)

Weathered basalt fragment

Basalt, a fine-grained mafic volcanic rock composed mainly of plagioclase and pyroxene, with possible olivine and iron-oxide alteration

Quartz crystal (likely clear quartz)

Quartz, silicon dioxide (SiO₂)