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

Quartzite

Quartzite (primarily SiO2)

Chert (often called Flint or River Pebble)

Chert (Microcrystalline Quartz, SiO2)

Chert (Jasper)

Microcrystalline Quartz (SiO2)

Granite

Phaneritic Igneous Rock (Granite)

Sandstone (Ferruginous)

Clastic sedimentary rock (primarily SiO2 with Fe2O3 cement)

Sunkissed Quartz or Hematoid Quartz

Silicon Dioxide (SiO2) with Hematite (Fe2O3) inclusions

Quartzite

Quartzite (SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Moss Agate

Silicon Dioxide (SiO2) with inclusions of Manganese or Iron oxide

Chert (variously known as Flint or River Pebble)

Microcrystalline or Cryptocrystalline Quartz (SiO2)

Chert (often called Flint)

Microcrystalline to cryptocrystalline quartz (SiO2)

Lapis Lazuli

Lapis lazuli (Mainly Lazurite: Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2)

Lapis Lazuli

Lapis Lazuli (Complex silicate mixture including Lazurite: (Na,Ca)8(AlSiO4)6(S,Cl,SO4,OH)2)

Lepidolite

Lepidolite (K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2)

Chert (specifically Red Chert or Jasper)

Microcrystalline Quartz (SiO2)

Lapis Lazuli

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

Quartz Pebble (Grit)

Silicon Dioxide (SiO2)

Milky Quartz with Iron Staining

Quartz (Silicon Dioxide, SiO2)

Sandstone (Pebble)

Arenite (primarily SiO2)

Granite

Phaneritic Igneous Rock (primarily Quartz, Feldspar, and Mica)

Sodalite

Na8(Al6Si6O24)Cl2

Quartzite (Yellow/Orange variety)

Quartzite (primarily SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Coarse-grained Quartz with Feldspar inclusions

Crystalline Quartz (SiO2) with Orthoclase/Plagioclase Feldspar inclusions

Painted Pet Rock (Quartzite/Sandstone base)

Silicon Dioxide (SiO2) with anthropomorphic acrylic embellishments

Milky Quartz Pebble with Chert

Silicon Dioxide (SiO2)

Garnet Schist

Almandine Garnet in Schist (X3Al2(SiO4)3)

Sandstone Beach Pebble

Clastic Sedimentary Rock (primarily Quartz with Iron Oxide coating)

Chert (var. Jasper)

Microcrystalline Quartz (SiO2)

Fluorite

Calcium Fluoride (CaF2)

Quartz Geode Fragment

Silicon Dioxide (SiO2)

Fossilized Crinoid Stem

Class Crinoidea (Echinodermata)

Amethyst (Druzy Quartz)

Amethyst (Silicon Dioxide - SiO2 with iron impurities)

Red Jasper

Silicon Dioxide (SiO2) containing Iron Oxide inclusions

Fossiliferous Limestone with Rugose Coral

Lithostrotionella (Limestone Matrix - CaCO3)

Quartz (Chert/Chalcedony Variety)

Silicon Dioxide (SiO2)

Quartz pebble

Silicon Dioxide (SiO2)

Chert (Jasper/Flint variety)

Microcrystalline Quartz (SiO2)

Asphalt Chunk (with aggregate)

Bituminous concrete / Anthropogenic conglomerate

Garnet Schist

Almandine-mica schist

Granite Cobble

Phaneritic Felsic Igneous Rock

Petrified Wood

Silicified Wood (SiO2)