Mineral (Or Mineraloid If Microcrystalline)

Ruby (in costume jewelry context)

Corundum (Al2O3) with Chromium impurities

Amber (Dark/Black Variety)

Succinite (Resinite), C10H16O

Quartz on Basalt

Silicon Dioxide (SiO2) on Mafic Igneous Rock

Sandstone

Clastic sedimentary rock (primarily SiO2)

Chrysocolla in Matrix

Hydrated copper silicate - (Cu,Al)2H2Si2O5(OH)4·nH2O

Quartz / Calcite Vein Rock

Silicon Dioxide (SiO2) or Calcium Carbonate (CaCO3)

Ferruginous Sandstone

Ferruginous Clastic Sedimentary Rock

Sandstone

Arenite (composed primarily of SiO2)

Sandstone (with prominent jointing/fractures)

Arenite (composed primarily of SiO2)

Orange Calcite

Calcium Carbonate (CaCO3)

Sandstone

Arenite (primarily SiO2)

Sandstone (with Iron Staining)

Clastic sedimentary rock (primarily SiO2 with Fe2O3 oxides)

Quartz Pebble (Water-worn)

Silicon Dioxide (SiO2)

Blue Sapphire (Synthetic or Man-made Glass Imitation)

Corundum (Al2O3) if natural; Lead-glass or Spinal if synthetic

Tufa (Vesicular Limestone)

Tufa (form of Calcium Carbonate, CaCO3)

Yellow Quartz Pebble (Citrine or Iron-Stained Quartz)

Silicon Dioxide (SiO2)

Iron (Hematite variety)

Iron (Fe) / Hematite (Fe2O3)

Amber (Rough Baltics/Beach Specimen)

Succinicum (Organic Gemstone - Fossilized Resin)

Sedimentary Breccia

Breccia (Clastic Sedimentary Rock)

Sandstone

Arenite (primarily SiO2)

Basalt

Basalt (Mafic Extrusive Igneous Rock)

Blue Chalcedony (likely dyed)

Silicon Dioxide (SiO2) - Cryptocrystalline Quartz

Sandstone

Arenite (SiO2 based)

Blue Sphalerite (likely dyed or treated Druzy Quartz/Agate)

Zinc Sulfide (ZnS) or Silicon Dioxide (SiO2) with trade-name enhancement

Amethyst

Silicon Dioxide with Iron impurities (SiO2)

Sandstone with Algae Growth

Arenite with Chlorophyta/Lichen

Shale (or Mudstone)

Siltstone/Argillite (composed mainly of clay and silt-sized particles)

Howlite (Dyed Turquoise)

Calcium Borosilicate Hydroxide (Ca2B5SiO9(OH)5)

Amber (Copal)

Fossilized Tree Resin (C10H16O)

Sandstone (Quartzite-rich)

Clastic sedimentary rock (SiO2 primary)

Chalcedony (Agate/Jasper mix in host rock)

Chalcedony (cryptocrystalline Silicon Dioxide, SiO2)

Hematite

Iron(III) oxide (Fe2O3)

Sandstone (Quartz Arenite)

Sandstone (Chemical formula: primarily SiO2)

Sandstone (Ferruginous)

Arenite (composed primarily of SiO2 with Fe2O3 cement)

Shale

Fissile mudstone (primarily clay minerals and silt-sized quartz)

Glauconitic Sandstone

Glauconitic Sandstone (complex silicate formula: (K,Na)(Fe,Al,Mg)2(Si,Al)4O10(OH)2)

Sandstone

Clastic sedimentary rock (primarily SiO2)

Aquamarine

Beryl (Be3Al2Si6O18)

Sandstone (Quartzose)

Arenite (primarily SiO2)

Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2)

Amethyst

Silicon Dioxide (SiO2) with iron impurities

Purple Dyed Agate Geode (Banded Chalcedony)

Silicon Dioxide (SiO2) - variety: Agate