Not A Rock (Synthetic Material)

Chert

Microcrystalline quartz (SiO2)

Scoria

Scoria (a vesicular basalt or andesite)

Ferruginous Sandstone (Gozzan)

Iron-rich clastic sedimentary rock with Limonite/Goethite

Slate

Metamorphosed Shale (Fine-grained Foliated Metamorphic Rock)

Flint Arrowhead

Cryptocrystalline quartz (Chert/Flint, SiO2)

Chert (Iron-stained)

Microcrystalline Quartz (SiO2)

Mixed rock and mineral gravel

Predominantly granite/granodiorite, basaltic rocks, quartz, and possible gneiss; exact identification is uncertain from the image

Petrified Wood

Silicified Wood (primarily SiO2)

Sandstone (Nut-stone / Cup-stone artifact)

Quartz Arenite / Worked Sedimentary Rock

Conglomerate (Red Sandstone variety)

Clastic Sedimentary Rock (Conglomeratic Sandstone)

Diorite

Diorite (Intermediate intrusive igneous rock)

Sandstone (Quartz Sandstone)

Clastic sedimentary rock (primarily SiO2)

Diorite

Diorite (Intermediate intrusive igneous rock)

Diorite

Diorite (Intermediate intrusive igneous rock)

Small polished brown stone

Indeterminate; possibly tumbled jasper, brown agate, or another iron-stained silicate

Ferruginous Sandstone

Clastic Sedimentary Rock with Iron Oxide Cement

Lapis Lazuli

Lapis Lazuli (Aggregate primarily of Lazurite: (Na,Ca)8(AlSiO4)6(S,SO4,Cl,1-2) with Calcite and Pyrite)

Botryoidal chalcedony (gray agate/jasper-like silica)

Microcrystalline quartz, SiO₂; likely chalcedony with opaque quartz or jasper inclusions

Quartzite with Hematite

Metamorphosed Quartz Sandstone (SiO2 with Fe2O3 inclusions)

Pink Granite

Phaneritic intrusive igneous rock with dominant Alkali Feldspar

Quartzite Beach Pebble

Metamorphosed Quartz Sandstone (SiO2)

Unidentified dark pebble

Undetermined; possibly polished basalt, chert, or iron-rich stone

Basalt with Mineral Vein (Cobble)

Basalt (with likely Quartz/Calcite vein)

Obsidian

Volcanic Glass (Extrusive Igneous Rock, primarily SiO2)

Chert (specifically Flint or Dark Chalcedony)

Silicon Dioxide (SiO2)

Iron-rich brown stone, possibly weathered chert or ironstone

Undetermined; likely iron-oxide-bearing silica-rich rock (chert/ironstone)

Chert

Microcrystalline Quartz (SiO2)

Chert (Iron-stained)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (Yellow Jasper/Flint)

Microcrystalline Quartz (SiO2)

Ferruginous Sandstone

Sandstone (enriched with Iron Oxide)

Sandstone (Quartz-rich Pebble)

Arenite (primarily SiO2)

Weathered limestone or calcitic fossil/reef fragment

Calcite-rich limestone (CaCO₃), possibly fossiliferous limestone

Brick

Fired clay or Ceramic material (no specific mineralogical scientific name as it's a composite)

Pumice

Pumice (Vesicular Felsic Igneous Rock)

Chert (Iron-stained Flint / Jasper)

Microcrystalline Quartz (SiO2) with Iron Oxides

Milky Quartz

Silicon Dioxide (SiO2)

Schist

Mica Schist

Ironstone Concretion / Goethite-Hematite Nodule

Goethite/Hematite (α-FeO(OH) / Fe2O3)

Laterite

Laterite (Iron and aluminum-rich residual rock)

Basalt

Basalt; fine-grained mafic volcanic rock composed mainly of plagioclase and pyroxene, commonly with olivine

Quartz (Grain)

Silicon Dioxide (SiO2)

Granodiorite

Granodiorite (Intermediate intrusive igneous rock)