Anthropogenic (Man Made)

Polished white chalcedony or milky quartz pebble

Chalcedony, microcrystalline quartz (SiO₂), possibly with iron-oxide staining or a minor mineral inclusion

Likely quartz cabochon in a ring

Quartz (SiO₂), possibly clear or milky quartz; identification is uncertain from the photograph

Weathered, iron-stained rock (likely metamorphic)

Indeterminate from photograph; possibly quartz-rich gneiss or schist

Chert (likely jasper/chalcedony-rich chert)

Microcrystalline quartz, SiO₂

Polished orbicular jasper (likely ocean jasper)

Siliceous microcrystalline quartz/chalcedony with iron-oxide and volcanic inclusions; commonly called ocean jasper

Lapis Lazuli

A metamorphic rock primarily composed of lazurite (Na,Ca)8[(S,SO4,Cl)2|(Al6Si6O24)], calcite (CaCO3), and pyrite (FeS2).

Chert / Flint

Silicon Dioxide (SiO2)

Fossiliferous limestone, possibly coral-bearing

Calcitic limestone (mostly CaCO₃; fossil fragments may include ancient colonial coral or shell material)

Chert (Flint)

Microcrystalline Quartz (SiO2)

Chert (often called Flint)

Chert (Cryptocrystalline Quartz, SiO2)

Granite fragment

Granite

Rounded basalt pebble

Basalt; fine-grained mafic volcanic rock, commonly dominated by plagioclase and pyroxene with possible olivine

Seraphinite

Clinochlore (Mg,Fe)5Al(AlSi3O10)(OH)8 - specific variety for Seraphinite due to its fibrous inclusions and chatoyancy.

Weathered, iron-stained rhyolite pebble (possibly rhyolitic volcanic breccia)

Rhyolite, a felsic volcanic rock; mainly quartz and alkali feldspar with minor plagioclase, altered mafic minerals, and iron-oxide staining

Weathered fossil shell fragment

Indeterminate bioclastic carbonate, likely molluscan shell (calcium carbonate, commonly aragonite or calcite)

Dark, mica-rich metamorphic rock (possibly schist)

Mica schist, tentatively; exact identification is limited by the small, partly obscured specimen

Quartzite or Quartz Vein Material

SiO2

Weathered basalt pebble

Basalt, a fine-grained mafic volcanic rock composed mainly of plagioclase, pyroxene, and commonly olivine or iron oxides

Pink Granite

Phaneritic Igneous Rock (Quartz-Feldspar-Mica)

Tumbled gray chalcedony (likely agate or quartzite)

Microcrystalline quartz, SiO₂ (chalcedony)

Quartz

Quartz (SiO₂)

Porphyritic Basalt or Diabase with Plagioclase Phenocrysts

Porphyritic Basalt or Diabase; Mineral: Plagioclase Feldspar

Water-worn pebble, likely fine-grained volcanic rock

Unidentified mafic volcanic rock; possibly andesite or basalt

Dark rounded stone, likely basalt pebble

Basalt, predominantly plagioclase and pyroxene; exact identification is uncertain from the image

Tiny amber-colored crystal or mineral fragment

Indeterminate from image; possibly quartz, citrine, topaz, or iron-stained feldspar

Granite

Granite (composed primarily of silica-rich minerals like quartz and feldspar)

Chert Pebble

Microcrystalline Quartz (SiO2)

Pumice

Vesicular volcanic rock, primarily silica-rich volcanic glass (commonly rhyolitic or dacitic)

Quartz (likely Milky Quartz)

Quartz (SiO₂ - Silicon Dioxide)

Likely basalt or dark volcanic rock

Fine-grained mafic igneous rock, probably basalt; exact identification requires testing

Black basalt or dark volcanic rock fragment

Likely basalt, composed chiefly of plagioclase feldspar and pyroxene, with possible magnetite

Granite fragment

Granite

Granite

Intrusive Igneous Rock (composed primarily of quartz, alkali feldspar, and plagioclase)

Chert (Flint)

Microcrystalline Silica (SiO2)

Tumbled chalcedony (likely agate or jasper fragment)

Microcrystalline quartz, SiO₂ (chalcedony)

Weathered pegmatite or feldspar-rich granite fragment

Granitic pegmatite, composed mainly of potassium feldspar and quartz, with minor mica; exact identification is uncertain from the photograph

Granite

Felsic Plutonic Rock

Likely dark basalt or mafic rock

Basalt; primarily plagioclase feldspar, pyroxene, and commonly olivine or magnetite

Granite

Felsic Intrusive Igneous Rock

Granite

Felsic intrusive igneous rock

Granite Pebble

Igneous Intrusive Rock (Quartz-Feldspar-Mica Phenocrysts)

Granite

Granite (Phaneritic Igneous Rock)