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

Chert (specifically Tan/Gray Chert)

Microcrystalline quartz (SiO2)

River Pebble (Greywacke or Quartzite-rich Sandstone)

Lithic Sandstone (primarily SiO2 with rock fragments)

Crazy Lace Agate

Silicon Dioxide (SiO2) - Chalcedony variety

Limestone (specifically Travertine or Tufa)

Calcium Carbonate (CaCO3)

Yellow Quartz (Citrine or Iron-Stained Quartz)

Silicon Dioxide (SiO2)

Quartz (Chert/Chalcedony variety)

Silicon Dioxide (SiO2)

Quartz (Citrine or Iron-stained Quartz)

Silicon Dioxide (SiO2)

White Marble

Recrystallized Calcite (CaCO3)

Limestone (specifically Dolomitic/Crystalline Limestone)

Sedimentary Carbonate Rock (CaCO3 / CaMg(CO3)2)

Amethyst

SiO2 (Silicon Dioxide)

Aragonite (Onyx Marble)

Aragonite / Calcium Carbonate (CaCO3)

Quartz

Quartz (SiO2, Silicon Dioxide)

Botryoidal Agate / Chalcedony Geode

Silicon Dioxide (SiO2)

Geode (Unopened)

Siliceous Concretion / Geode

Chevron Amethyst

Silicon Dioxide (SiO2) with Iron impurities

Amethyst

SiO2 (Silicon Dioxide with Iron impurities)

Fish Fossil in Limestone

Lycoptera (likely) in Micritic Limestone

Banded Calcite (often sold as 'Travertine' or 'Mexican Onyx')

Calcium Carbonate (CaCO3)

Banded Agate (Chert/Chaldcedony)

Silicon Dioxide (SiO₂)

Limestone (Flagstone)

Fossiliferous Limestone (CaCO3)

Quartzite (River Pebble)

Metamorphosed Quartz Sandstone (primarily SiO2)

Quartzite

Quartzite (primarily SiO2)

Quartz (Double-Terminated)

Silicon Dioxide (SiO2)

Mookaite Jasper

Siliceous (chert) sedimentary rock, a form of Jasper

Fluorite (likely Fluorite on Quartz/Matrix)

Calcium Fluoride (CaF2)

Amethyst (vibrant lilac/purple variety)

Silicon Dioxide (SiO2) with iron impurities

Quartz / Limestone Gravel

SiO2 (Silicon Dioxide) and CaCO3 (Calcium Carbonate)

Chert (often called Flint when dark)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Quartz Geode

Silicon dioxide (SiO2)

Citrine

Citrine (Silicon Dioxide, SiO2)

Amethyst

Amethyst (Silicon Dioxide, SiO2)

Fluorite (Durango Fluorite)

Calcium Fluoride (CaF2)

Mixed collection of Quartz varieties, Chalcedony, and metamorphic pebbles

Mixed gemstones (primarily Silicon Dioxide - SiO2)

Amethyst

Silicon Dioxide (SiO2) with Iron impurities

Chert (specifically a weathered Chert nodule or fragment)

Chert; Microcrystalline or Cryptocrystalline Quartz (SiO2)

Quartzite

Quartzite (SiO2)

Geode (Unopened)

Siliceous Septarian Concretion / Geode (SiO2)

Amazonite

Potassium aluminum silicate (KAlSi3O8)

Quartzite River Rock

Metamorphic Quartzite (primarily SiO2)

Crinoid Fossil in Limestone

Crinoid (Class Crinoidea) in Fossiliferous Limestone (CaCO3)

Mookaite Jasper

Silicified Radiolarite (SiO2)

Calcite

Calcium Carbonate (CaCO3)