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

Brecciated Chert

Brecciated Chert (Microcrystalline Quartz, SiO2)

Sandstone (Quartzose Sandstone Pebble)

Arenite (primarily SiO2)

Moss Agate

Chalcedony (Silicon Dioxide / SiO2)

Ferruginous Quartz

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

Chert (Jasper variation)

Microcrystalline Quartz (SiO2)

Chert (Tan/Yellow variety)

Microcrystalline Quartz (SiO2)

Chert (Flint variety)

Microcrystalline Silica (SiO2)

Gastly (Trick or Trade Halloween Series)

Cellulose-carbonaceous composite (Lignocellulose laminated with pigmentary polymers)

Red Quartzite (River Pebble)

Quartzite (primarily Silicon Dioxide - SiO2)

Sodalite

Sodalite (Na8Al6Si6O24Cl2)

Chert / Flint (a variety of Chert)

Chert (SiO2)

River Cobble (Gneiss/Migmatite)

Gneissic Metamorphic Rock (composed mainly of Quartz, Feldspar, and Biotite)

Sandstone (specifically Arkose or Quartz Arenite)

Arenite (primarily SiO2 with possible Feldspar)

Amethyst

SiO2 (Silicon Dioxide)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Star Sapphire

Corundum (Al2O3) with Rutile inclusions

Septarian Nodule (Septarian Dragon Stone)

Septarian Concretion (Composition: Calcite, Aragonite, and Limestone/Clay)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Massive Quartz

Silicon Dioxide (SiO2)

Clear Quartz

Silicon Dioxide (SiO2)

Chert (specifically a nodule with Chalcendony/Agate banding)

Microcrystalline Quartz (SiO2)

Clear Quartz Crystal Cluster

Silicon Dioxide (SiO2)

Apatite

Apatite group mineral (e.g., Fluorapatite - Ca5(PO4)3F, Chlorapatite - Ca5(PO4)3Cl, Hydroxylapatite - Ca5(PO4)3(OH))

Pebble (likely Sandstone or Granitic Pebble)

Clastic Sediment (or specific rock type, e.g., Arenite, Granitoid Pebble)

Pyrite in Quartz (Drill Core)

Silicon Dioxide (SiO2) with Iron Sulfide (FeS2) inclusions

Sandstone (likely Graywacke or Arkose variant)

Clastic Sedimentary Rock (SiO2 with assorted lithic fragments)

Botryoidal Goethite on Quartz

Goethite (α-Fe3+O(OH)) on Quartz (SiO2)

Chert (Field Stone)

Chert (Silicon Dioxide, SiO2)

Quartz Druzy Geode

Silicon Dioxide (SiO2) - Crystalline Variety

Jasper (brecciated or orbicular variety)

Silicon dioxide (SiO2) with iron oxide inclusions

Red Jasper

Jasper (Silicate mineral - SiO2)

Chert (Nodule)

Microcrystalline Quartz (SiO2)

Tree Agate

Silicon Dioxide (SiO2) with Chlorite inclusions

Basalt Pebble

Extrusive Mafic Igneous Rock

Fossilized Gastropod in Chert/Limestone

Internal mold of Gastropoda (Class) with CaCO3 or SiO2 mineral formula

Banded Calcite (often commercially called 'Mexican Onyx')

Calcium Carbonate (CaCO3)

Jasper (Milky/Cream Variety)

Silicon Dioxide (SiO2) - variety of Chalcedony

Lapis Lazuli

Na6Ca2(Al6Si6O24)(SO4,S,Cl,OH)2 (Lazurite-dominated rock)

Quartzite (clastic/metamorphic subtype)

Quartzite (primarily Silicon Dioxide, SiO2)

Quartz (Smoky/Milky Variety)

Silicon Dioxide (SiO2)

Jasper with Quartz Veining

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Quartzite

Quartzite (primarily SiO2)