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

Common Marble

Calcium Carbonate (CaCO3)

Sandstone (Ferruginous)

Clastic Sedimentary Rock (Litharenite)

Limestone (Brecciated/Recrystallized)

Calcium Carbonate (CaCO3)

Quartz Geode (Druzy)

Crystalline Silicon Dioxide (SiO2)

Sparkling Druzy Quartz on Matrix

Silicon Dioxide (SiO2) with iron oxide inclusions

Chert (Common Opal/Agate inclusion)

Microcrystalline Quartz (SiO2)

Chert (Nodule)

SiO2 (Microcrystalline Quartz)

Chert (Arrowhead Preform or Flake)

Microcrystalline Quartz (SiO2)

Chert / Flint

Cryptocrystalline Quartz (Silicon Dioxide, SiO2)

Quartz (Iron-Stained)

Silicon Dioxide (SiO2)

Fossiliferous Limestone

CaCO3 (principally Calcite or Aragonite)

Honey Calcite

Calcium Carbonate (CaCO3)

Dendritic Agate (River Pebble)

Silicon Dioxide (SiO2) with Manganese or Iron oxide inclusions

Chalcopyrite in Quartz (Gossan/Iron Hat)

CuFeS2 (Chalcopyrite) with SiO2 (Quartz)

White Opal (Common)

Hydrated Silica (SiO2·nH2O)

Sandstone (Gneissic or Banded)

Clastic Sedimentary Rock (composed predominantly of SiO2)

Fossiliferous Limestone

Biogenic Limestone (Calcium Carbonate, CaCO3)

Lapis Lazuli

Lazurite-rich metamorphic rock (complex silicate)

Limestone Pebble

Sedimentary Calcium Carbonate (CaCO3)

Yellow Calcite

Calcium Carbonate (CaCO3)

Fossiliferous Limestone (Coquina / Shell Limestone)

Biogenic Limestone (Calcium Carbonate, CaCO3)

Fossiliferous Limestone

Calcium Carbonate (CaCO3) with fossil inclusions

Sandstone (with potential trace fossils)

Clastic sedimentary rock (primarily SiO2)

Sandstone (Iron-stained)

Arenite (composed primarily of SiO2 with Fe2O3 staining)

Amethyst

Quartz (SiO2) with trace iron impurities

Fossiliferous Limestone

Limestone (CaCO3 - Calcium Carbonate)

Chert (and Limestone)

Silicon Dioxide (SiO2)

Quartzite

Quartzite (SiO2 silicon dioxide)

Chert (River Pebble)

Microcrystalline quartz (SiO2)

Orange Quartzite (River Pebble)

Quartzite (primarily SiO2)

Chert (Flint)

Microcrystalline Quartz (SiO2)

Sandstone (Quartzose Sandstone)

Clastic sedimentary rock (primarily SiO2)

Quartzite (specifically an iron-stained or Carnelian-colored variety)

Silicon Dioxide (SiO2) with iron oxide inclusions

Chert (Iron-Stained)

Microcrystalline Quartz (SiO2)

Foliated Gneiss (River-Worn Pebble)

Gneiss (High-grade Regional Metamorphic Rock)

Yellow Calcite

Calcium Carbonate (CaCO3)

Banded Agate

Cryptocrystalline Quartz (SiO2)

Amethyst (Quartz)

SiO2 (Silicon Dioxide)

Chert (Grey-Green Var.)

Silicon Dioxide (SiO2)

N/A - Non-Geological Item

Sandstone

Clastic sedimentary rock (primarily SiO2)

Amethyst

SiO2 (Silicon Dioxide) - a variety of Quartz