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

Crinoid Fossil in Limestone

Class Crinoidea in Carbonate Matrix (CaCO3)

Quartzite

Quartzite (SiO2)

Green Tourmaline

Verdelite (Silicate mineral); Na(Li,Al)3Al6(BO3)3Si6O18(OH)4

Purple Dyed Agate Geode (Banded Chalcedony)

Silicon Dioxide (SiO2) - variety: Agate

Orange Calcite

Calcium Carbonate (CaCO3)

Amethyst

Silicon Dioxide (SiO2) with iron impurities

Geode (unopened)

Chert / Chalcedony Geode (SiO2)

Chert Nodule (Commonly known as Flint or River Rock)

Silicon Dioxide (SiO2)

Banded Chert in Matrix

Microcrystalline Quartz (SiO2)

Blue Lace Agate (with Amethyst Geode center)

Silicon Dioxide (SiO2) - Cryptocrystalline Chalcedony

Quartz

Quartz (Silicon Dioxide - SiO2)

Green Calcite

Calcium Carbonate (CaCO3)

Amethyst

Amethyst (Silicon Dioxide with Iron impurities, SiO2)

Blue Calcite

Calcite (CaCO3)

Dendritic Agate or Manganese Nodule in Chert/Limestone

Silicon Dioxide (SiO2) with Manganese Oxide (MnO2) inclusions

Marble

Recrystallized Calcite / Dolomite (CaCO3)

Travertine (Tufa)

Chemical Sedimentary Limestone (CaCO3)

Quartz Pebble

Silicon Dioxide (SiO2)

Calcite (or Alabaster, if truly carved)

Calcium Carbonate (CaCO3)

Porphyritic Basalt (with Amygdales)

Amygdaloidal Porphyritic Basalt

Quartz (Milky/Gray variety)

Silicon Dioxide (SiO2)

Graphite

Graphite (Native Carbon, C)

Lapis Lazuli

Lapis Lazuli (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2

Amethyst

SiO2 (Silicon Dioxide)

Quartz

SiO₂ (Silicon Dioxide)

Green Fluorite

Fluorite (Calcium Fluoride, CaF2)

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Chert (Arrowhead)

Chert (primarily Microcrystalline Silica, SiO2)

Lapis Lazuli

Lazurite-rich metamorphic rock ((Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2)

Amethyst

Silicon Dioxide (SiO2) with iron impurities

Marble

Recrystallized Calcite (CaCO3)

White Marble

Recrystallized Calcite / Calcium Carbonate (CaCO3)

Sandstone (Quartzose)

Arenite (primarily SiO2)

Chert Pebble

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Limestone

Calcium Carbonate (CaCO3)

Orange Calcite

Calcium Carbonate (CaCO3)

Fossilized Bivalve Shell

Bivalvia (fossil specimen)

Dyed Pumice

Vesicular Rhyolite (Artificial Coloration Addition)

Quartz Vein on Matrix

Silicon Dioxide (SiO2)

Granite with Orthoclase and Hematite Staining

Phaneritic Felsic Igneous Rock (primarily SiO2 with KAlSi3O8)

Zebra Jasper

Silicon Dioxide (SiO2) - Macro-crystalline Quartz/Chert with impurities

Citrine (Heat-treated Amethyst)

Silicon Dioxide (SiO2) with iron impurities