The Purple Specimen Is A Mineral (Amethyst); The White Specimen Is A Sedimentary Rock (Limestone Or Marble).

Blue John Fluorite

Fluorite (Calcium Fluoride), CaF2

Granite Gneiss

Gneiss (High-grade regional metamorphic rock)

Quartzite (River Pebble)

Meta-quartzite (composed primarily of SiO2)

Quartz / Milky Quartz

Silicon Dioxide (SiO2)

Porphyry

Porphyritic Andesite/Basalt

Gneiss (specifically a Banded Gneiss cobble)

Gneiss (composed mainly of Quartz, Feldspar, and Biotite/Amphibole)

Sandstone (Quartzite-rich)

Clastic Sedimentary Rock (primarily SiO2)

Chert (Jasper/Flint variety)

Microcrystalline Quartz (SiO2)

Chert (Nodular Chert)

Microcrystalline Silica (SiO2)

Quartzite

Quartzite (SiO2)

Quartz (Iron-stained or Rose variant)

Silicon Dioxide (SiO2)

River Stone (Chalcedony/Jasper variety)

Microcrystalline Quartz (SiO2)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Botryoidal Quartz

Silicon Dioxide (SiO2)

Chert Nodule (River Cobble)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Puddingstone (Gowganda Tillite/Jasper Conglomerate)

Jasper Conglomerate (SiO2 primary composition)

Chert / Flint Pebble

Silicon Dioxide (SiO2)

Jasper in Quartz (River Cobble)

Silicon Dioxide (SiO2) with Ferric Iron inclusions

Chert (varieties include Flint or Jasper)

Chert (cryptocrystalline quartz; SiO₂)

Leopard Skin Jasper

Jasper (Silicon Dioxide with impurities), SiO2

Chalcedony (Botryoidal)

Silicon Dioxide (SiO2)

Milky Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

Ferruginous Quartz

Silicon Dioxide (SiO2) with Iron Oxide (Fe2O3) inclusions

Chert (varieties include Flint and Jasper)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Quartz (Vein Quartz)

Silicon Dioxide (SiO2)

Dendritic Agate

Silicon Dioxide with Manganese/Iron oxide inclusions (SiO2)

Ferruginous Sandstone (Ironstone)

Sedimentary rock with high iron oxide content (Fe2O3 / FeO(OH))

Chert (Jasper-like Silicate)

Microcrystalline quartz (SiO2)

Quartzite

Quartzite (primarily SiO2)

Chert (Cherty Flint)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Yellow Quartz (Citrine or Quartzite Pebble)

Silicon Dioxide (SiO2)

Ametrine

Ametrine (SiO2 - Silicon Dioxide with trace amounts of Iron)

Quartz (Clear/White)

Silicon Dioxide (SiO2)

Gneiss (specifically a weathered or stream-worn specimen)

Gneiss (Foliated Metamorphic Rock)

Quartz (Milky/Gravel variety)

Silicon Dioxide (SiO2)

Chert (Nodule)

Chert (Silicon Dioxide, SiO2)

Chert (Red Jasper)

Microcrystalline Quartz (SiO2)

Chert (Jasper/Quartzite river pebble)

Microcrystalline Silica (SiO2)

Snowflake Obsidian

Volcanic glass with Phenocrysts (SiO2 with Cristobalite inclusions)

Gneiss

Gneiss

Gneiss

Foliated Metamorphic Gneiss