Sedimentary (Or Mineraloid)

Orange Quartzite (River Pebble)

Quartzite (primarily SiO2)

Yellow Quartz Pebble (Citrine or Iron-stained Quartz)

Silicon Dioxide (SiO2)

Honey Calcite Geode Segment

Calcite (Calcium Carbonate, CaCO3)

Fossilized Sea Urchin (Echinoid)

Echinoidea (Class); commonly Clypeasteroida for sand dollar types

Limonite (often after Hematite or Goethite)

Limonite (FeO(OH)·nH2O)

Limonite (with Goethite/Ironstone)

FeO(OH)·nH2O (Hydrated Iron Oxide)

Druzy Quartz on Host Rock

Silicon Dioxide (SiO2)

Chert (or Flint)

Chert (cryptocrystalline quartz), SiO2

Black Opal

Hydrated Silica (SiO2·nH2O)

Limonite (Iron Ore)

FeO(OH)·nH2O (Hydrated Iron Oxide)

Petrified Wood

Silicified Wood (primarily SiO2)

Puddingstone

Conglomerate (specifically a type of jasper conglomerate or quartz conglomerate)

Leopardskin Jasper

Jasper (a variety of microcrystalline Quartz)

River Stone / Pebble

Clastic Sediment (composed largely of Quartz, Feldspar, and various rock fragments)

Magnetite

Magnetite (Fe3O4)

Quartz (likely) or a Quartzite Pebble

Silicon dioxide (SiO2) for quartz. If it's quartzite, it's a metamorphic rock primarily composed of quartz.

Celestine (or Celestite) Geode

Strontium Sulfate (SrSO4)

Quartz (Clear Quartz)

Silicon Dioxide (SiO2)

Chert (Tan/Grey variety)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Pyrite

Iron Sulfide (FeS2)

Clear Quartz (Rock Crystal)

Quartz (Silicon Dioxide, SiO2)

Chert (Field-collected Arrowhead-shaped Fragment)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Green Jasper

Jasper (Silicates, SiO2)

Galena

Lead Sulfide (PbS)

Blue Apatite

Fluorapatite (Ca5(PO4)3F)

Optical Calcite (Iceland Spar)

Calcium Carbonate (CaCO3)

Jasper with Dendritic Inclusions

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Agate

Silicon Dioxide (SiO2) - variety Chalcedony

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Pyrite (Fools Gold)

Iron Sulfide (FeS2)

Amethyst Geode

Silicon Dioxide (SiO2) with iron impurities

White Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

Chert (Jasper/Common Opal mix)

Microcrystalline Quartz (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Chalcedony (Botryoidal)

Silicon Dioxide (SiO2)

Clear Quartz Cluster

Silicon Dioxide (SiO2)

Mixed Tumbled Gemstones and River Rocks

Mixed Decorative Stones (predominantly Silicon Dioxide - SiO2 variants)

Picture Jasper

Silicon Dioxide (SiO2) with iron oxide inclusions

Turquoise

Hydrated phosphate of copper and aluminium [CuAl6(PO4)4(OH)8·4H2O]

Blue Apatite

Apatite (Calcium Phosphate) - Ca5(PO4)3(F,Cl,OH)

Pyrite

Iron Disulfide (FeS2)

Yellow Jasper

Jasper (Silicon Dioxide, SiO2)