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

Yellow Jasper

Silicon Dioxide (SiO2) - Opaque Chalcedony

Green Agate

Silicon Dioxide (SiO2) - Chalcedony variety

Milky Quartz (with Iron staining)

Silicon Dioxide (SiO2)

Quartz (River Pebble)

Silicon Dioxide (SiO2)

Clear Quartz

Silicon Dioxide (SiO2)

Polygenetic Conglomerate (Puddingstone)

Conglomerate (SiO2 matrix with mixed clasts)

Chert (Nodule)

Silicon Dioxide (SiO2)

Biotite (Black Mica)

Biotite (K(Mg,Fe++)3AlSi3O10(OH,F)2)

Fluorite with Rhodochrosite

Fluorite (CaF2) and Rhodochrosite (MnCO3)

Blue Dyed Agate Geode Slice

Chalcedony (Silicon Dioxide, SiO2) with artificial cobalt/iron-based dye

Septarian Nodule

Septarian Concretion (Calcium Carbonate/Aragonite/Calcite)

Rose Quartz

Silicon Dioxide (SiO2)

Chert (Jasper/Flint variant)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Desert Rose

Gypsum (variety Selenite) or Barite, CaSO4·2H2O

Lepidolite

K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2 (Lithium-bearing Phyllosilicate)

Howlite (White Buffalo Turquoise)

Howlite (Calcium Borosilicate Hydroxide), Ca2B5SiO9(OH)5

Granite

Granite (Felsic Plutonic Rock)

Red Sandstone

Arenite with Hematite cementation

Schist

Mica Schist

Flower Jasper

Agatized Fossil Coral / Chalcedony (SiO2)

White Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

Banded Sandstone (Liesegang Rings)

Sedimentary sandstone with Iron oxide precipitates

Quartzite

Quartzite (chiefly SiO2)

Sandstone (Banded)

Clastic Sedimentary Rock (primarily SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Sandstone (with Iron Staining)

Clastic sedimentary rock (primarily SiO2)

Jasper (Yellow/Brown variety)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Yellow Jasper

Silicon Dioxide (SiO2) - Impure Cryptocrystalline Quartz

Jasper

Jasper (Silicon Dioxide, SiO2)

Granite Pebble

Granite (Phaneritic intrusive igneous rock comprising Quartz, Feldspar, and Mica)

Pyrite in Quartz

Iron Disulfide (FeS2) in Silicon Dioxide (SiO2)

Blue Lace Agate

Silicon Dioxide (SiO2)

Granite

Plutonic Igneous Rock (composed of Quartz, Alkali Feldspar, and Plagioclase)

Sandstone (Greywacke)

Sandstone (SiO2 enriched with lithic fragments)

Limestone

Calcium Carbonate (CaCO3)

Coquina

Bioclastic Limestone

Fluorite

Fluorite (CaF₂)

Fossil Coral

Scleractinia (Anthos), primarily Calcium Carbonate (CaCO3)

Feldspar-rich Granite (Pink Granite)

Phaneritic Felsic Igneous Rock

Manganese-coated Sandstone

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

Mixed Mineral Specimens

Mixed Silicates, Oxides, and Phosphates (SiO₂, Ca₅(PO₄)₃(F,Cl,OH), Na₈Al₆Si₆O₂₄Cl₂, etc.)

Chert (Smooth River Pebble)

Silicon Dioxide (SiO2)