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

Fluorite

Fluorite (CaF₂)

Quartzite Pebble (River Rock)

Quartzite (mainly SiO2)

Chert (Smooth River Pebble)

Silicon Dioxide (SiO2)

Manganese-coated Sandstone

Clastic sedimentary rock with Manganese Oxide (often Pyrolusite or Psilomelane)

Greywacke (River Slikkenstone)

Greywacke (Impure Sandstone)

Amygdaloidal Basalt with Quartz/Zeolite Infill

Amygdaloidal Basalt (extrusive volcanic rock with SiO2 or CaAl2Si3O10·3H2O infill)

Quartzite / Sandstone / Chert Mix

Silicon Dioxide (SiO2)

Granite (Pegmatitic)

Phaneritic Felsic Igneous Rock

Limestone

Sedimentary Calcium Carbonate (CaCO3)

Quartz Geode

Silicon Dioxide (SiO2)

Amethyst (Digital/Conceptual Representation)

Amethyst (Silicon Dioxide with iron impurities, SiO2)

Dendritic Agate (also known as Dendritic Siltstone or Mudstone)

Silicon Dioxide with Manganese/Iron Oxide inclusions (SiO2 + MnO2)

Chert (and Flint variant)

Chert (SiO2)

Limestone

Calcium Carbonate (CaCO3)

Quartz (Vein Quartz)

Silicon Dioxide (SiO2)

Sandstone with Liesegang Rings

Arenite with secondary Iron oxide (Limonite/Goethite) precipitation

Ferruginous Sandstone (Ironstone)

Sandstone with Hematite/Goethite cement (SiO2 + FeO(OH))

Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

Limestone

Calcium Carbonate (CaCO3)

Opalite

Synthetic Opalite Glass (Silicon Dioxide)

Yellow Agate

Chalcedony (cryptocrystalline Quartz), SiO2

Agate / Banded Chalcedony

Agate (Silicon Dioxide / SiO2)

Banded Chert (River Stone)

Silicon Dioxide (SiO2)

Quartz / Quartzite

Quartz (Silicon Dioxide, SiO2)

Milky Quartz Pebble

Silicon Dioxide (SiO2)

Crinoid and Coral Fossils in Limestone

Fossiliferous Limestone with Rugosa (order) and Crinoidea (class)

Jasper

Silicon Dioxide (SiO2)

Chert (Iron-stained)

Microcrystalline or cryptocrystalline Quartz (SiO2)

Quartz Druzy (on Matrix)

Silicon Dioxide (SiO2)

River Siltstone Pebble

Siltstone (primarily composed of silica and clay minerals)

Granite Pebble

Granite (Felsic Plutonic Rock)

Gastropod Fossil (Snail Steinkern)

Class Gastropoda fossil, composed of Calcium Carbonate (CaCO3)

Fluorite (likely)

Calcium Fluoride (CaF2)

Quartz Geode

Silicon Dioxide (SiO2)

Flint

Chert (a form of cryptocrystalline quartz, chemical formula SiO₂)

Petrified Wood

Silicified Wood (primarily SiO2)

Chert (specifically a Worked Flint/Knapped Flake)

Chert / Flint (Microcrystalline Quartz, SiO2)

Limestone

Calcium Carbonate (CaCO3)

Charoite

Charoite - K(Ca,Na)2Si4O10(OH,F)·H2O

Pyrite in Shale

Iron Sulfide (FeS2) in Argillaceous Shale

Charoite

Charoite (K(Ca,Na)2Si4O10(OH,F)·nH2O)

Clear Quartz Crystal

Quartz (Silicon Dioxide, SiO2)