Man Made Material, Not A Natural Rock Or Mineral Specimen

Basalt

Mafic Volcanic Rock (composed of plagioclase, pyroxene, and olivine)

Amygdaloidal Basalt with Epidote/Chlorite

Basalt (containing (Ca2(Al2Fe3+)(SiO4)(Si2O7)O(OH)))

Milky Quartz (Druzy Geode fragment)

Silicon Dioxide (SiO2)

Chalcedony (Quartz Nodule)

Silicon Dioxide (SiO2)

Sandstone Concretion

Clastic Sedimentary Concretion (primarily SiO2 with Fe2O3 cement)

Foliated Gneiss (River-Worn Pebble)

Gneiss (High-grade Regional Metamorphic Rock)

Kimberlite

Kimberlite (Potassic ultramafic igneous rock)

Dendritic Agate

Silicon Dioxide with Manganese/Iron oxide inclusions (SiO2)

Bauxite

Bauxite (mixture of Hydrous Aluminum Oxides)

Granite

Phaneritic Felsic Igneous Rock

Carnelian

Carnelian (Microcrystalline Quartz, SiO2)

Bumblebee Jasper

Calcite-bearing Volcanic Tuff containing Sulfur and Arsenic (Orpiment/Realgar)

Granite Pebble (Salt and Pepper Granite)

Phaneritic Felsic Igneous Rock (primarily Quartz, Feldspar, and Biotite/Amphibole)

Granite Cobble

Felsic Intrusive Igneous Rock (Granite)

Fossiliferous Limestone

Calcareous biomicrite / Bioclastic limestone

Granite Pegmatite

Coarse-grained Granite (SiO2 - Aluminum and Alkalies)

Pink Granite

Phaneritic plutonic rock (dominated by Alkali Feldspar)

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Quartzite with Hematite

Metamorphosed Quartz Sandstone (SiO2 with Fe2O3 inclusions)

Jasper

Silicon Dioxide (SiO2) with impurities (mostly Iron Oxides)

Amygdaloidal Basalt with Agate/Chalcedony Infills

Amygdaloidal Basalt (Composition: SiO2 and (Mg,Fe)2SiO4 in matrix; SiO2 in amygdule)

Dendritic Agate (or Dendritic Opal)

SiO2 (for Agate), SiO2·nH2O (for Opal)

Clear Quartz (Rock Crystal)

Silicon Dioxide (SiO2)

Dendritic Agate

Chalcedony (SiO2) with manganese/iron oxide inclusions

Aquamarine

Beryl (Be3Al2Si6O18 with trace Fe2+)

Clear Quartz (Crystal Quartz)

Silicon Dioxide (SiO2)

Conglomerate

Conglomerate (Detrital sedimentary rock)

Milky Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

Granite

Granite (Phaneritic intrusive igneous rock)

Gneiss (Metamorphic Rock)

Gneiss

Red Granite

Phaneritic Plutonic Rock (High Potassium Feldspar)

Pumice

Pumice (a highly vesicular extrusive igneous rock)

Sandstone

Clastic Sedimentary Rock (composed mostly of SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Amethyst Geode

Amethyst (Silicon Dioxide), Formula: SiO2

Banded Gneiss

Gneiss (High-grade Regional Metamorphic Rock)

Quartz (Crystal/Druzy Quartz)

Quartz (SiO₂)

Serpentinite

Serpentinite (composed primarily of Serpentine group minerals, Mg3Si2O5(OH)4)

Quartz Vein in Host Rock (clastic sediment)

Silicon Dioxide (SiO2) in matrix

Quartz Pebble

Silicon Dioxide (SiO2)

Milky Quartz Pebble

Quartz (Silicon Dioxide - SiO2)

Nuummite

Nuummite (Orthorhombic amphiboles: Anthophyllite and Gedrite)