Unknown (Likely Sedimentary Or Metamorphic)

Quartz fragment

Quartz (silicon dioxide, SiO₂)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Brown quartz-rich pebble (likely chert or weathered quartzite)

Quartz (SiO₂), possibly microcrystalline quartz/chert or quartzite

Milky Quartz Vein in Host Rock

Silicon Dioxide (SiO2)

Limonite pseudomorph after Pyrite

Goethite/Limonite FeO(OH)·nH2O

Polished granitic pebble

Granite, composed chiefly of quartz, feldspar, and mica/amphibole

Quartz (Small Fragment)

Silicon Dioxide (SiO2)

Quartz Vein in Matrix (Breccia / Host Rock with Quartz)

Silicon Dioxide (SiO2) in Host Rock Matrix

Unidentified weathered rock fragments

Likely mixed silicate rocks; specific identification requires testing

Yellow chalcedony or quartz fragment

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

Greenish Metamorphic Rock (likely containing epidote or chlorite)

Metamorphic rock, possibly epidosite or greenstone

Tumbled chalcedony (likely milky quartz)

Microcrystalline quartz, SiO₂; possibly pale agate or quartzite

Foliated metamorphic cobble, likely gneiss

Biotite–quartz–feldspar gneiss (tentative)

Weathered quartz-rich rock, likely chert or quartzite

Microcrystalline quartz (SiO₂), possibly with iron-oxide staining

Dark gray metamorphic rock, likely hornfels or fine-grained amphibolite

Hornfels/amphibolite; commonly quartz, feldspar, amphibole, biotite, and minor sulfides

Pyrite-bearing rock (iron pyrite)

Pyrite, FeS₂, likely disseminated or massive in a host rock

Quartz crystal (likely clear quartz)

Quartz, silicon dioxide (SiO₂)

Red Jasper

Silicon Dioxide (SiO2) with Iron Oxide inclusions

Banded gneiss cobble

Gneiss, commonly quartz–feldspar–mica gneiss

Dark metamorphic rock, likely biotite schist or hornblende-bearing gneiss

Probable mica schist/amphibolite; composition may include biotite, amphibole, quartz, feldspar, and iron oxides

Granitic Gneiss

Gneiss (containing Potassium Feldspar and Quartz)

Quartz heart (likely milky/included quartz)

Quartz, silicon dioxide (SiO₂)

Banded metamorphic rock, likely gneiss

Biotite–quartz–feldspar gneiss, possibly migmatitic

Quartz-rich rock fragment

Milky quartz, primarily silicon dioxide (SiO₂), possibly quartzite or a feldspar-bearing vein rock

Rounded river pebble

Unidentified fine-grained clastic rock, possibly sandstone or mudstone

Metallic sulfide ore, likely pyrite-bearing rock

Pyrite (FeS₂), possibly with chalcopyrite and quartz/host rock

Quartz (Milky or Citrine-tinted)

Silicon Dioxide (SiO2)

Garnet (likely Almandine)

Almandine (Fe3Al2(SiO4)3)

Rounded greenish river pebble

Indeterminate; possibly weathered greenstone, basalt, or serpentinized ultramafic rock

Weathered metamorphic rock, likely gneiss or schist

Indeterminate foliated silicate rock; commonly quartz–feldspar–mica assemblage

Quartz with iron staining

Silicon dioxide (SiO2)

Small pale mineral fragment

Unidentified; possibly quartz, calcite, or feldspar

Pyrite-bearing sulfide specimen

Pyrite (FeS₂), possibly mixed with chalcopyrite or other iron sulfides

Rounded stream pebbles (likely quartzite and iron-stained sandstone)

Quartzite (SiO₂), with a possible ferruginous sandstone pebble (quartz + iron oxides)

Weathered quartz-bearing rock, possibly calcite vein fragment

Indeterminate; likely quartz (SiO₂) with carbonate minerals such as calcite (CaCO₃)

Tan quartz-rich rock, likely sandstone or weathered quartzite

Quartz sandstone; primarily SiO₂ with possible feldspar and iron-oxide cement

Likely weathered quartz-rich rock fragments

Uncertain; visually consistent with massive quartz or quartz-bearing sandstone

Rounded sedimentary pebble, likely mudstone or shale

Argillite/mudstone; predominantly compacted clay minerals with quartz and iron oxides

Quartz-rich rock, possibly milky quartz or quartzite fragment

Quartz (SiO₂), potentially quartzite if metamorphic

Quartz-rich pegmatitic rock, probably granitic gneiss

Quartz–feldspar–mica gneiss; locally pegmatitic granite

Gneiss (Granitic Gneiss)

Gneiss

Rounded gray river pebble, likely fine-grained basalt or andesite

Basaltic-andesitic volcanic rock; commonly plagioclase feldspar, pyroxene, and minor iron oxides