Mineraloid (Man Made Origin)

Black Marble with Quartz Veining

Metamorphosed Limestone (Recrystallized CaCO3)

Peridotite (Dunite)

Olivine-rich Peridotite ((Mg,Fe)2SiO4)

Porphyritic Rhyolite (Red Porp)

Porphyritic Rhyolite (Felsic volcanic rock)

Blue Quartzite

Quartzite with inclusions (SiO2)

Agate (or Chalcedony)

SiO2 (Silicon Dioxide) - a cryptocrystalline variety of quartz

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2)

Jasper

Silicon Dioxide (SiO2) with impurities

Chert (Holey Stone)

Microcrystalline Quartz (SiO2)

Granitic Gneiss

Gneiss (High-grade Metamorphic Rock)

Jasper with Agate and Quartz Inclusions

Silicon Dioxide (SiO2) - Chalcedony / Quartz aggregate

Moss Agate

Chalcedony (Silicon Dioxide, SiO2) with inclusions

Obsidian

Volcanic glass (high silica content based on SiO2)

Quartz (Clear / Rock Crystal)

Silicon Dioxide (SiO2)

Sandstone

Arenite

Granite (Leucogranite)

Felsic Plutonic Rock (Granite)

Milky Quartz Pebble

Silicon Dioxide (SiO2)

Green Fluorite

Calcium Fluoride (CaF2)

Red Sandstone

Arenite (primarily Quartz, SiO2, with Iron Oxide cementing agent)

Fluorite

Calcium fluoride (CaF2)

Sandstone (Greywacke)

Clastic Sedimentary Rock (SiO2 with lithic fragments)

Serpentine

Serpentinite (a rock composed primarily of serpentine minerals like antigorite, chrysotile, and lizardite; general formula (Mg, Fe)3Si2O5(OH)4)

Dendritic Agate

Silicon Dioxide (SiO2) with manganese/iron inclusions

Agate (Plume/Moss variety)

Cryptocrystalline Quartz (SiO2) with iron/manganese inclusions

Quartz (Common or Milky Quartz)

Silicon Dioxide (SiO2)

Jasper (Red Jasper with Quartz veins)

Jasper (Silicon Dioxide, SiO2)

Brown Jasper (Chert)

Silicon Dioxide (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Granite

Phaneritic intrusive igneous rock (consisting mainly of Quartz, Alkali Feldspar, and Plagioclase)

Banded Iron Formation (BIF) / Tiger Iron

Ferruginous Chert (primarily Quartz [SiO2] and Hematite/Magnetite [Fe2O3/Fe3O4])

Red Quartzite Cobble

Quartzite (primarily SiO2)

Quartzite

Quartzite (primarily SiO2)

Quartz (River Pebble)

Silicon Dioxide (SiO2)

Amethyst

Amethyst (Silicon Dioxide, SiO2)

Hematite (Iron Ore)

Hematite (Fe2O3)

Sandstone (Red Sandstone)

Arenite (primarily Quartz with Hematite cement)

Slickenside

Tectonic Fault Scarp Surface

Tiger's Eye (commonly referred to as Blue/Gold Tiger's Eye)

Tiger's Eye is a variety of Chalcedony (cryptocrystalline quartz), SiO2, exhibiting chatoyancy. The blue variety is often called Hawk's Eye.

Wood Jasper

Siliceous sedimentary rock (variety of Chert/Chalcedony)

Quartz (specifically Milky/White Quartz)

Silicon Dioxide (SiO2)

Drupa or Druzy Quartz on Geode Fragment

Crystalline Silicon Dioxide (SiO2)

Granite

Felsic Plutonic Rock (Granite)

Gold Nugget

Native Gold (Au)