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

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2)

Milky Quartz

Quartz (Silicon Dioxide - SiO2)

Apatite

Apatite Group (e.g., Fluorapatite Ca5(PO4)3F, Chlorapatite Ca5(PO4)3Cl, Hydroxylapatite Ca5(PO4)3(OH))

Bumblebee Jasper

Calcite-Auripigment-Pyrite-Realgar assemblage (Carbonate/Sulphide mixture)

Sandstone

Arenite (composed primarily of SiO2)

Chert (Yellow Jasper/Agatized Chert)

Microcrystalline Quartz (SiO2)

Chalcedony Geode Fragment

Microcrystalline Quartz (SiO2)

Porphyry

Porphyritic Andesite/Dacite

Pink Quartzite

Quartzite (primarily SiO2)

Limestone

Calcium Carbonate (CaCO3)

Clear Quartz Crystal Cluster

Silicon Dioxide (SiO2)

Jasper with Quartz Veining

Silicon Dioxide (SiO2) with iron oxide inclusions

Basalt Porphyry

Porphyritic Basalt

Agate

Silicon dioxide (SiO2)

Yellow Quartz (Citrine Quartz or Yellow Chalcedony)

Silicon Dioxide (SiO2)

Chert

Microcrystalline Quartz (SiO2)

Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

Greenstone / Serpentinite

Serpentinite (composed primarily of minerals from the serpentine group Mg3Si2O5(OH)4)

Carnelian

Carnelian (a variety of Chalcedony, SiO2)

Snowflake Obsidian

Vitreous Volcanic Rock (Amorphous Silicate), SiO2

Sandstone (Micaceous/Feldspathic variant)

Arenite (specifically subarkose or lithic arenite)

Ferruginous Sandstone (Gozzan)

Iron-rich clastic sedimentary rock with Limonite/Goethite

Sandstone (Ferruginous)

Arenite (with high iron oxide content)

Sandstone (Quartz Sandstone)

Arenite (primarily SiO2)

Quartz with Chalcopyrite and Pyrite

Silicon Dioxide (SiO2) with Copper Iron Sulfide (CuFeS2)

Quartz Druze (on Matrix)

Silicon Dioxide (SiO2)

Carnelian Agate (with Quartz/Chalcedony)

Silicon Dioxide (SiO2) - Microcrystalline Quartz

Amethyst (Purple), Sulfur (Yellow), and Blue Apatite

SiO2 (Quartz), S (Native Sulfur), Ca5(PO4)3(F,Cl,OH) (Apatite Group)

Chert / Flint (with Crinoid Stem Molds)

Microcrystalline Quartz (SiO2)

Druzy Quartz on Milky Quartz

Silicon Dioxide (SiO2)

Quartz (Pale Rose or Milky Variety)

Silicon Dioxide (SiO2)

Quartzite

Quartzite (primarily SiO2)

Orange Quartz (Citrine or Iron-stained Quartz)

Silicon Dioxide (SiO2)

Chert (Field Stone/Jasper variety)

Microcrystalline Quartz (SiO2)

Chert (Jasper/Flint variety)

Silicon Dioxide (SiO2)

Orange Calcite

Calcium Carbonate (CaCO3)

Yellow Quartz (or Citrine Quartz)

Silicon Dioxide (SiO2)

Banded Agate (specifically Carnelian Agate slice)

Chalcedony (cryptocrystalline variety of Quartz), SiO2

Pegmatite with Schorl (Black Tourmaline) and Mica

Pegmatite (complex association of NaAlSi3O8, NaFe3Al6(BO3)3Si6O18(OH)4, and KAl2(AlSi3O10)(OH,F)2)

Limestone

Calcium Carbonate (CaCO3)

Basalt with Calcite Veins

Basalt (containing CaCO3 inclusions)

Banded Chert (Jasper)

Silicon Dioxide (SiO2)