Mineral In A Matrix (Likely Quartz Or Feldspar)

Glacially transported granite and gneiss boulders

Granite (quartz–feldspar–mica); banded specimens likely gneiss

Weathered quartz-rich rock, likely quartzite or milky-quartz vein material

Quartzite (dominantly SiO₂), possibly quartz-vein breccia with iron-oxide staining

Quartz-rich granite or granitic pegmatite fragment

Granite; predominantly quartz (SiO₂), feldspar, and minor mica/iron oxides

Likely raw rose quartz or pink feldspar fragment

Quartz (SiO₂), possibly pink feldspar such as orthoclase

Quartz-bearing granite or granitic pegmatite

Coarse felsic intrusive rock, chiefly quartz (SiO₂), feldspar, and mica; exact identification requires testing

Granite Pegmatite with Tourmaline and Muscovite

Pegmatite (Feldspar: KAlSi3O8, Quartz: SiO2, Schorl: NaFe2+3Al6(Si6O18)(BO3)3(OH)3(OH))

Unidentified polished mineral fragment

Likely quartz-bearing stone; exact identification is impossible from the blurred photograph

Quartz-bearing granite or pegmatitic rock

Granite, composed mainly of quartz, feldspar, and mica; exact identification is uncertain from the image

Polished banded gneiss

Biotite–quartz–feldspar gneiss, locally migmatitic

Native gold-bearing rock (probable gold nugget/ore fragment)

Native gold, Au, associated with quartz and/or iron oxides

Quartz-bearing pegmatite specimen

Quartz (SiO₂) with feldspar and mica, likely granitic pegmatite

Weathered granitic cobble

Granite to granodiorite; chiefly quartz, feldspar, and biotite/hornblende

Porphyritic Basalt River Stone

Porphyritic Basalt

Basalt with Quartz/Calcite Inclusion

Aphanitic Mafic Igneous Rock (Basalt) with SiO2 or CaCO3 vein

Weathered, veined rock fragment (likely granite or gneiss)

Probable granitic gneiss; quartz–feldspar–mica assemblage

Black-and-white granitoid pebble

Likely granite or granodiorite; quartz + feldspar + dark biotite/amphibole

Astrophyllite in matrix

(K,Na)3(Fe,Mn)7Ti2Si8O24(O,OH)7

Weathered granite or granitic gneiss

Granite; quartz + feldspar + biotite/hornblende, possibly weakly gneissic

Quartz, Sandstone, and Siltstone specimens

Silicon Dioxide (SiO2) and Clastic Sedimentary Rocks

Rounded dark pebble, likely basaltic andesite

Fine-grained mafic volcanic rock; probable basalt or andesite, identification uncertain from image alone

Fluorite on Matrix

Calcium Fluoride (CaF2)

Weathered granite or granitic gneiss

Quartz–feldspar–mica granite; possibly weakly foliated granitic gneiss

Tumbled feldspar-rich pebble (probable)

Likely potassium feldspar, orthoclase or microcline (KAlSi₃O₈), though the photograph is not diagnostic

Milky quartz with iron-stained mica

Quartz (SiO₂), likely intergrown with muscovite and minor iron oxides

Weathered granite-like rock

Coarse-grained granitic rock, likely quartz–feldspar–mica aggregate

Beryl (Aquamarine) in Matrix

Beryllium aluminum silicate (Be3Al2(SiO3)6)

Smoky quartz crystal/rough fragment

Quartz (SiO₂), likely smoky quartz

Granitic Pegmatite with Graphic Texture

Graphic Granite (alkali feldspar and quartz intergrowth)

Quartz-encrusted Matrix

Silicon Dioxide (SiO2) with Ferruginous Sandstone

Amazonite in Quartz

K(AlSi3O8) - Potassium Feldspar with Quartz (SiO2)

Weathered metamorphic rock, likely mica schist or gneiss

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

Amygdaloidal Rhyolite (often called Lake Superior Agate relative)

Rhyolite with Calcite/Quartz amygdules (SiO2 and secondary minerals)

Weathered quartz-rich rock, possibly pegmatite

Likely quartz–feldspar pegmatite; exact identification is uncertain from the image

Gneiss (with Quartz Vein / Pegmatite Banding)

Metamorphic Gneiss

Pegmatitic granite, strongly weathered

Granite/pegmatite composed mainly of quartz, feldspar, and mica

Pink Granite

Plagioclase-Quartz-K-Feldspar Granite

Quartz-rich pegmatite (likely feldspar–quartz–mica rock)

Granitic pegmatite; chiefly quartz (SiO₂), potassium feldspar (KAlSi₃O₈), and mica

Quartz-rich rock, likely milky quartz with iron staining

Mostly quartz (SiO₂); exact rock type cannot be confirmed from the image

Gneiss

Foliated quartz–feldspar gneiss, commonly with biotite or amphibole

Copper-bearing chrysocolla/azurite host rock (probable)

Chrysocolla, Cu₂H₂Si₂O₅(OH)₄·nH₂O, with possible azurite Cu₃(CO₃)₂(OH)₂ in iron-stained quartz/matrix

Basalt with Quartz Infill

Aphanitic Mafic Igneous Rock with Silica (SiO2) inclusion

Weathered granite fragment

Granite, chiefly quartz, feldspar, and mica