Sedimentary Rock (Metamorphosed)

Quartzite Pebble

Metamorphosed Quartz Sandstone (SiO2)

Greenstone / Epidosite

Epidosite (primary minerals: Epidote and Quartz)

Weathered granite or granitic gneiss

Granite/granitic gneiss; chiefly quartz, feldspar, and mica

Likely blue-gray slate

Slate, a fine-grained rock composed mainly of mica-group minerals and quartz

Biotite-bearing granite or granitic gneiss

Quartz–feldspar–biotite granitoid; exact identification requires testing

Quartzite (with mineral vein)

Metamorphosed Quartz-rich Sandstone (SiO2)

Rounded gray-green pebble, likely basalt or fine-grained metamorphic rock

Probable basalt (plagioclase–pyroxene–iron oxide aggregate); exact identification requires testing

Quartz-bearing granite or granitic pegmatite

Crystalline quartz (SiO₂) with feldspar and dark mica/amphibole; likely weathered granite

Greenstone Porphyry

Altered Porphyritic Andesite/Basalt

Quartzite

Quartzite (primarily SiO2)

Light-colored granite or granitic gneiss

Granite; primarily quartz (SiO₂), feldspar, and minor mica, possibly with gneissic fabric

Likely purple quartzite or purple chert

Quartzite/chert, predominantly microcrystalline SiO₂; exact identification requires testing

Tumbled tan quartzite or chert pebble

Quartzite, predominantly microcrystalline quartz (SiO₂); possibly chert, also SiO₂

Likely tumbled white quartz or quartzite pebble

Quartz (SiO₂), possibly quartzite

Tiger iron slab (likely polished banded iron formation)

Banded iron formation (BIF), chiefly hematite/magnetite, quartz, and iron-rich amphibole or jasper

Greenstone pebble (identification uncertain from photo)

Greenstone, typically metamorphosed mafic rock composed of chlorite, actinolite, and epidote

Serpentine-rich greenstone (probable serpentinized ultramafic rock)

Serpentinite; chiefly serpentine-group minerals (Mg₃Si₂O₅(OH)₄), commonly with magnetite, chromite, and relict olivine/pyroxene

Iron-stained quartzite or ironstone pebble

Quartzite (mostly SiO₂) with iron-oxide/hydroxide minerals, likely hematite/goethite

Veined quartz-bearing metamorphic rock

Likely quartzite or siliceous schist with iron-oxide staining

Banded Slate (Sedimentary Pebble)

Slate (Metamorphosed Shale or Mudstone)

Riverstone Quartzite (Water-worn Siltstone/Quartzite)

Metamorphosed Quartz-rich Arenite (SiO2)

Weathered quartz-rich pebble, possibly quartzite or granite fragment

Quartzite (mostly SiO₂), though the specimen may contain feldspar and other silicates

Greenstone, likely serpentinite

Serpentinite; predominantly serpentine-group minerals, Mg₃Si₂O₅(OH)₄, with possible magnetite, chlorite, and talc

Greenstone Porphyry

Porphyritic Metavolcanic Rock

Likely hornblende-rich amphibolite

Amphibolite, composed chiefly of hornblende (amphibole) and plagioclase feldspar

Rounded river cobble, likely quartzite

Quartzite (chiefly recrystallized quartz, SiO₂); exact identification is uncertain from the image

Grey-green granitic gneiss (possibly granitoid basement rock)

Felsic orthogneiss; mainly quartz, K-feldspar/plagioclase, and biotite/amphibole

Rounded gray river cobble

Likely fine-grained sandstone, siltstone, or metamorphosed equivalent; exact identification requires a fresh surface and tests

Quartzite with Calcite Accretion

Metamorphosed Quartz Sandstone (SiO2 with CaCO3 coating)

Blue Quartzite (Blue Aventurine)

Silicon Dioxide (SiO2) with inclusions of Dumortierite or Magnesio-riebbeckite

Honey calcite (optical calcite)

Calcite, calcium carbonate (CaCO₃)

Weathered ultramafic rock, likely serpentinite

Serpentinite; chiefly serpentine-group minerals (Mg₃Si₂O₅(OH)₄), with magnetite and possible olivine/pyroxene remnants

Foliated slate or phyllite

Fine-grained metamorphosed mudstone; typically quartz, mica, chlorite, and clay-derived minerals

Likely weathered granite or granitic gneiss

Granite: quartz–feldspar–mica aggregate; possibly foliated gneiss

Graphite-rich schist (probable graphite ore)

Graphite schist; chiefly graphitic carbon (C) with quartz, mica, and possibly feldspar

Inspirational River Stone (Quartzite)

Metamorphosed Quartz-rich Rock (Quartzite) with SiO2 composition

Granite or granitic gneiss

Granite; mainly quartz, potassium feldspar, plagioclase, and mica

Weathered quartz-rich metamorphic rock (likely gneiss or quartzite)

Quartz (SiO₂) with probable feldspar, mica, and iron-oxide alteration

Shatter Cone

Impactite (Shatter Cone texture)

Iron-stained quartz-rich rock, possibly ferruginous quartzite

Quartz-rich ferruginous rock; exact lithology cannot be determined from the image alone

Weathered quartz-rich rock, possibly milky quartz or quartzite

Quartz (SiO₂); likely quartzite if the grains are recrystallized and fused

Weathered quartz-rich rock fragment

Likely microcrystalline quartz with iron-oxide staining; exact identification is uncertain from the image