Sedimentary Rock (Metamorphosed)

Marble

Marble (metamorphosed limestone or dolostone), primarily composed of calcite (CaCO3) or dolomite (CaMg(CO3)2)

Quartzite (River Pebble)

Metamorphosed Quartz Sandstone (SiO2)

Greenstone pebble (likely altered basalt or serpentine)

Greenschist-facies mafic rock; commonly chlorite–actinolite–epidote ± serpentine

Biotite-rich granite or granitic gneiss

Quartz–feldspar–biotite granite; possibly foliated granitic gneiss

Lichen-covered granite or granitic gneiss

Granite: quartz + feldspar + mica; possibly gneiss if foliation is confirmed

Biotite-bearing granite or granitic gneiss

Quartz–feldspar–biotite rock; probable granite (locally gneissic)

Quartzite Pebble

Metamorphosed Quartz Sandstone (SiO2)

Quartzite

Metamorphosed Sandstone (Mainly SiO2)

Rounded gray metamorphic cobble, likely quartzite or gneiss

Quartz-rich metamorphic rock; possibly quartzite (mostly SiO₂) or banded gneiss

Greenstone (likely chlorite-rich metamorphic rock)

Chlorite-rich greenschist; exact identification requires testing

Gray Slate Pebble

Slate (metamorphosed mudstone/shale)

River Cobble (likely Metasedimentary or Basalt)

Metamorphosed Siltstone or Altered Fine-grained Igneous Rock

Quartzite (Ferruginous)

Metamorphosed Quartz Sandstone (SiO2)

Dark granite or granitic gneiss slab

Quartz–feldspar–biotite granite; possibly foliated granitic gneiss

Marble

Metamorphosed Limestone (principally CaCO3)

Quartzite

Metamorphosed Quartz Sandstone (SiO2)

Weathered quartz-rich rock, likely arkose or quartzite

Quartz-dominant siliciclastic rock; probable arkose (quartz + feldspar), possibly weakly metamorphosed quartzite

Green Quartzite / Aventurine

SiO2 (Metamorphosed Quartz Sandstone)

Quartzite with Vugs

Metamorphosed Quartz Sandstone (SiO2)

Foliated metamorphic rock, likely marble or calc-schist

Calcite-rich marble/calc-schist; predominantly CaCO₃ (calcite), with possible mica and quartz

Small rounded quartz-rich pebble

Likely quartz-bearing chert or weathered quartzite; exact identification requires testing

Likely weathered granite or granitic gneiss fragment

Granite–gneiss, chiefly quartz, feldspar, and mica

Calcite-rich limestone (likely crystalline limestone/marble)

Calcite, CaCO₃; likely recrystallized carbonate rock

Tumbled brown stone, likely quartzite or jasper

Indeterminate; probable quartz-rich aggregate (SiO₂), possibly brown jasper

Stream-worn greenstone (likely serpentinite or altered basalt)

Serpentinite, chiefly serpentine-group minerals; possibly chlorite–actinolite greenstone

Greenstone / epidote–chlorite schist (tentative)

Epidote–chlorite schist, likely containing actinolite and quartz/feldspar

Quartz-rich rock, likely milky quartz or quartzite

Quartz (SiO₂), possibly quartzite with minor iron-oxide inclusions

Granite or granitic gneiss

Quartz–feldspar–mica aggregate; possibly orthogneiss if the faint banding is structural

Tumbled blue stone, likely blue aventurine or dyed quartzite

Quartz (SiO₂), likely with inclusions or artificial dye; exact identification requires testing

Quartz-rich feldspathic rock, likely granite or granitic gneiss

Granite/granitic gneiss; chiefly quartz (SiO₂), feldspar, and minor mica

Rounded quartz-rich river pebble

Likely quartzite or quartz-rich sandstone; exact identification requires testing

Quartzite (Yellow/Tan Quartz Cobble)

Metamorphosed Quartz Sandstone (SiO2)

Rounded gray limestone pebble with a calcite vein

Calcitic limestone, composed predominantly of calcite (CaCO₃), locally cut by a white calcite vein

Quartzite (River Stone)

Metamorphosed Quartz Sandstone (SiO2)

Honey calcite (orange calcite)

Calcite, calcium carbonate (CaCO₃)

Orange chromium diopside (likely tumbled)

Diopside, CaMgSi₂O₆; orange color may reflect iron-rich composition or surface treatment/inclusion

Rounded quartz-rich pebble

Likely quartzite or fine-grained quartz sandstone; exact identification requires testing

Rounded quartz-rich pebble

Likely quartzite or quartz-bearing sandstone; composition mainly SiO₂ with possible feldspar and iron-oxide impurities

Quartzite

Metamorphosed Quartz Sandstone (SiO2)

Quartzite Pebble

Metamorphosed Quartz-rich Sandstone (SiO2)

Weathered quartz-bearing rock, possibly granitic gneiss

Quartz–feldspar–mica aggregate; exact identification requires testing

Likely slate

Slate; fine-grained rock composed mainly of quartz, mica and/or chlorite