Synthetic Material (Not A Rock Or Mineral)

Chert / Flint

Microcrystalline quartz (SiO2)

Serpentinite (or Green Quartz Pebble)

Mg3Si2O5(OH)4 (Serpentine group) / SiO2 (Quartz mix)

Petrified Wood

Silicified Wood (SiO2)

Granite

Granitic intrusive igneous rock

Banded Gneiss

Gneiss (Metamorphic high-grade rock)

Milky Quartz

Silicon Dioxide (SiO2)

Petrified Wood (Black / Carbonized)

Silicon Dioxide (Quartz/Chalcedony replacing Organic Matter)

Quartzite Pebble

Metamorphosed Quartz Sandstone (SiO2)

Sandstone (Ferruginous)

Arenite (primarily SiO2 with iron oxide staining/cementing)

Basalt

Basalt (Mafic volcanic rock)

Granodiorite (Gneissic texture)

Granodiorite (containing Quartz SiO2, Plagioclase Feldspar, and Biotite)

Porphyritic rhyolite (likely lithophysal/vesicular rhyolite)

Rhyolite; chiefly quartz and alkali feldspar, with minor plagioclase and iron-bearing minerals

Diorite

Phaneritic intermediate plutonic rock

Diorite (River Cobble)

Phaneritic intermediate plutonic rock

Scoria (Basaltic Lava Rock)

Vesicular Basalt

Sandstone (Pebble)

Arenite (primarily SiO2)

Vesicular volcanic rock, possibly weathered basalt or scoria

Basaltic scoria/vesicular basalt; predominantly plagioclase, pyroxene, and iron-titanium oxides

Ferruginous Sandstone

Ferruginous Clastic Sedimentary Rock

Sandstone (Red Sandstone / River Stone)

Arenite (composed primarily of Quartz, SiO2, with Iron Oxide cementation)

Sandstone (Pebble)

Clastic sedimentary rock (SiO2 primary)

Quartz-rich pegmatitic rock (likely quartz–feldspar–mica specimen)

Granitic pegmatite; mainly quartz (SiO₂), feldspar, and dark mica/amphibole

Shale

Fissile Mudstone (primarily composed of clay minerals and quartz)

Likely iron-rich slag or weathered ironstone

Hematite–goethite-rich material (Fe₂O₃/FeO(OH)); possibly industrial iron slag

Slate

Metamorphic pelitic rock

Small polished brown stone

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

Ammonite Fossil (Small Pyritized or Calcitized Internal Mold)

Ammonoidea

Fossilized Coral (Petrified Coral)

Lithostrotionella (example genus) / Scleractinia

Rose Quartz

Silicon Dioxide (SiO2) with trace amounts of titanium, iron, or manganese

Quartz-rich hydrothermal ore rock, likely gold-bearing quartz vein

Milky quartz (SiO₂) with iron-oxide staining and probable sulfide minerals; host rock may be schist or altered granite

Tumbled red jasper

Jasper, an opaque microcrystalline variety of quartz (SiO₂), colored mainly by iron oxides

Mica Schist

Metamorphic Rock (rich in Muscovite or Biotite mica)

Granite

Phaneritic Felsic Igneous Rock (Granite)

Banded gneiss (weathered glacial erratic)

Gneiss; typically quartz–feldspar–biotite ± hornblende

Siltstone

Siltstone (primarily composed of quartz and clay minerals)

Sandstone (Ferruginous)

Arenite (with Hematite/Limonite cement)

Likely porphyritic igneous rock (possibly granite or rhyolite)

Quartz–feldspar–mica aggregate; exact identification requires a fresh surface and tests

Quartz-rich translucent pebble, possibly iron-stained quartz or chalcedony

Quartz (SiO₂), potentially microcrystalline quartz (chalcedony)

Sandstone (Quartz Sandstone)

Arenite (primarily SiO2)

Polished banded agate

Chalcedony (microcrystalline quartz), SiO₂

Ferrochrome Slag

Calcium-Aluminium-Magnesium Silicate Slag

Ferruginous Sandstone

Arenite with Iron-Oxide cement (Fe2O3 · nH2O)

Larimar

Pectolite [NaCa2Si3O8(OH)] with copper substitution