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

Geode (unopened)

Silica-filled Concretion (SiO2)

Orange Calcite

Calcium Carbonate (CaCO3)

Dream Amethyst (Chevron Amethyst)

Silicon Dioxide (SiO2) with Ferric Iron impurities

Amethyst (Chevron or Banded Amethyst)

Silicon Dioxide (SiO2) with trace Iron (Fe)

Sedimentary rock with quartz veining

Laminated siltstone or mudstone with hydrothermal quartz veins

Geode (Unopened)

Silica-rich Concretion (primarily SiO2)

Quartz (Milky/Crystal Variety)

Silicon Dioxide (SiO2)

Zebra Marble

Metamorphosed Alabaster/Limestone (CaCO3)

Amazonite

Potassium Feldspar (KAlSi3O8), specifically Microcline

Fossiliferous Limestone

Bioclastic Limestone (composition: CaCO3)

Septarian Nodule

Septarian Concretion

Chert (Jasper variety)

Silicon Dioxide (SiO2)

Charoite

Charoite; (K,Sr,Ba,Ca)15-16(Na,Ca)8(Si,Al)24O60(OH,F)4·nH2O

Blue Apatite

Fluorapatite (Ca5(PO4)3F)

Amethyst

Amethyst (SiO2 with iron impurities)

Quartz (likely) or a Quartzite Pebble

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

N/A (Non-Geological Specimen)

Limestone

Calcium Carbonate (CaCO3)

Garnet Schist or Garnet-bearing Quartzite

Metamorphic rock containing Almandine Garnet (Fe3Al2(SiO4)3) and Quartz (SiO2)

Amethyst

Silicon Dioxide (SiO2) with iron impurities

Quartz Druzy on Matrix (likely Agate or Jasper)

Silicon Dioxide (SiO2) with various mineral inclusions

Blue Spinel on Marble with Phlogopite

MgAl2O4 (Spinel) in CaCO3 (Calcite/Marble) matrix

Sandstone

Arenite (SiO2 dominant)

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Chevron Amethyst

Crystalline Silicon Dioxide with Iron impurities (SiO2)

Limestone (Weathered)

Calcium Carbonate (CaCO3)

Quartz Pebble (Chert/Chalcedony variety)

Silicon Dioxide (SiO2)

Sandstone with Secondary Mineral Encrustation

Arenite with Silica/Calcite deposits (SiO2 or CaCO3)

Amethyst

Amethyst (Silica mineral, SiO2)

Amethyst

Amethyst (Silicon Dioxide, SiO2 with Iron impurities)

Fossilized Brachiopod/Bivalve in Limestone

Brachiopoda or Bivalvia fossil in Calcite/Limestone (CaCO3)

Quartz Geode

Silicon Dioxide (SiO2)

Amethyst

Amethyst (Silicon Dioxide with Iron impurities), SiO₂

Fossiliferous Limestone with Crinoid stems

Calcite-rich Biogenic Sedimentary Rock (CaCO3)

Fluorite

Calcium Fluoride (CaF2)

Fossiliferous Limestone (Red Marble)

Bioclastic Limestone (CaCO3)

Chert (Yellow/Tan Variety)

Chert (SiO2)

Sandstone (with Lichen)

Arenite (composed primarily of SiO2)

Chert (Jasper)

Silicon Dioxide (SiO2)

Limestone (specifically Marl or Chalk)

Calcium Carbonate (CaCO3)

Chert (Yellow Jasper/Flint)

Silicon Dioxide (SiO2)

Quartzite (Pink/Red variety)

Quartzite (SiO2 with iron oxide impurities)