Rock (Likely Sedimentary)

Weathered sandstone or iron-rich sedimentary fragment

Quartz-rich sandstone, possibly ferruginous sandstone (SiO₂-dominant)

Chert (Flint)

Chert (SiO2)

Dark gray river pebble, likely basalt

Basalt; chiefly plagioclase feldspar, pyroxene, and minor olivine or magnetite

Yellow Quartzite (River Cobble)

Quartzite (mainly SiO2)

Shale with Trace Fossils

Fissile mudrock (Shale)

Shale

Fissile mudstone (rich in clay minerals and quartz)

Iron-stained quartzite or chert

Quartzite, predominantly SiO₂, with iron-oxide staining

Sandstone

Clastic Sedimentary Rock (Quartz arenite)

Sandstone

Clastic sedimentary rock (Quartz arenite)

Quartz Vein in Sandstone

Quartz (SiO2) in Clastic Sedimentary Rock

Banded Chert

Microcrystalline Quartz (SiO2)

Polished dark stone, likely basalt

Basalt; chiefly plagioclase feldspar, pyroxene, and commonly olivine

Likely metallic meteorite fragment

Unclassified iron-rich meteorite; possible stony-iron or iron meteorite

Granite (Alkali-feldspar rich)

Phaneritic Felsic Igneous Rock (Major components: KAlSi3O8, SiO2)

Shale

Sedimentary rock composed of clay minerals and quartz

Diorite (Dalmatian Stone)

Phaneritic Plutonic Diorite

Milky Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

Likely polished leopard-skin jasper or brecciated jasper

Jasper, an opaque microcrystalline variety of quartz (SiO₂), with iron-oxide and other mineral inclusions; exact variety cannot be confirmed from the image alone

Fossil-bearing limestone

Bioclastic limestone, likely containing a brachiopod or bivalve imprint

Porphyritic Basalt River Stone

Porphyritic Basalt

River Stone (likely Quartzite or Chert)

Recrystallized Silicon Dioxide (SiO2)

Sandstone Pebble

Sedimentary Rock (Quartz Arenite)

Gravel / Limestone Fragment

Calcium Carbonate (CaCO3) / Fine-grained Sedimentary Rock

Sandstone (Greywacke)

Sandstone (SiO2 enriched with lithic fragments)

Granite featuring Quartz Vein

Phaneritic Felsic Igneous Rock (Quartz, Orthoclase Feldspar, Mica)

Granite (Pink/Potassium-rich)

Phaneritic Plutonic Felsic Igneous Rock (primarily SiO2 with KAlSi3O8)

Greenstone (likely serpentinite or chlorite-rich metamorphic rock)

Probable serpentinite/chlorite schist; commonly dominated by serpentine-group minerals, chlorite, talc, and magnetite

Quartz-rich limestone or calcitic marble

Calcite (CaCO₃), possibly with quartz (SiO₂)

Worked chert (likely flint)

Microcrystalline quartz/chalcedony, SiO₂

Hag Stone (Adder Stone / Geode-bearing Pebble)

Sedimentary Rock with Cavity (often Quartzite, Limestone, or Sandstone)

Sandstone

Arenite

Tumbled orange calcite

Calcite (calcium carbonate, CaCO₃)

Sandstone Pebble

Sandstone (primarily Quartz, SiO2)

Pink feldspar-bearing granite or pegmatitic rock

Granite/pegmatite, chiefly quartz (SiO₂), potassium feldspar (KAlSi₃O₈), plagioclase, and dark mica/amphibole; pink areas may be K-feldspar or garnet.

Tumbled blue-green stone, likely chrysocolla-bearing jasper

Chrysocolla-rich chalcedony/jasper; commonly a mixture of chrysocolla (hydrated copper silicate, variable formula) and quartz (SiO₂)

Polished pink chalcedony (likely pink agate/geode)

Microcrystalline quartz, SiO₂; chalcedony with iron-bearing inclusions and possible druzy quartz

Amygdaloidal Rhyolite (often called Lake Superior Agate relative)

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

Shale (or Mudstone)

Clay mineral aggregate / Fine-grained siliciclastic sedimentary rock

Sandstone

Arenite (SiO2 primarily)

Yellow Quartz (Citrine/Yellow Jasper mix)

Silicon Dioxide (SiO2) with iron oxide inclusions

Granite or granitic gneiss

Felsic granitoid, chiefly quartz, feldspar, and mica; possibly weakly foliated gneiss

Coarse-grained Granite (Quartz and Feldspar dominated)

Granitoid (KAlSi3O8 – NaAlSi3O3 – CaAl2Si2O8 – SiO2)