Mineraloid

Snowflake Obsidian

Volcanic Glass with Spherulite Inclusions (70-75% SiO2)

Limonite (Iron Ore)

Limonite (Hydrous ferric oxides), generic formula FeO(OH)·nH2O

Pearl

Aragonite / Calcium Carbonate (CaCO3)

Opal (Precious Opal)

Hydrated Silica (SiO2·nH2O)

Limonitic Iron Ore / Goethite

Hydrated Iron(III) oxide-hydroxide (primarily FeO(OH)·nH2O)

Obsidian

Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)

Mahogany Obsidian

Volcanic Glass (predominantly SiO2 with inclusions of Hematite or Magnetite)

Limonite (Iron Ore)

Hydrated Iron(III) Oxide-Hydroxide (FeO(OH)·nH2O)

Mahogany Obsidian

Volcanic glass (SiO2 with Hematite or Magnetite inclusions)

Snowflake Obsidian

Volcanic glass with Cristobalite inclusions (mostly SiO2)

Shungite

Shungite (carbon-rich Precambrian mineraloid)

Obsidian (specifically Mahogany Obsidian)

Volcanic glass (high silica content, SiO2)

Obsidian

Obsidian (Volcanic Glass; SiO2 content > 70%)

Obsidian with Mahogany Phasing

Volcanic Glass (SiO2 + Fe2O3)

Obsidian

Obsidian (Volcanic Glass, SiO2 + impurities)

Limonite (Iron Stone/Goethite)

Limonite (mixture of hydrated iron oxides, primarily Goethite: α-FeO(OH))

Obsidian (Gold Sheen)

Obsidian (SiO2 + impurities)

Mahogany Obsidian

Volcanic glass containing Hematite or Magnetite (SiO2 + Fe2O3)

Mahogany Obsidian

Volcanic Glass (SiO2 + Fe2O3)

Obsidian

Volcanic Glass (SiO2 + impurities)

Pearl (Biogenic Mineraloid)

Calcium carbonate (Aragonite) and Conchiolin, CaCO3

Mahogany Obsidian

Volcanic Glass with Hematite/Magnetite inclusions

Snowflake Obsidian (Flower Jasper variant)

Vitreous volcanic silicate with cristobalite inclusions

Obsidian

Volcanic Glass (SiO2)

Mahogany Obsidian

Volcanic Glass (Silicate: SiO2 + Fe2O3)

Obsidian

Volcanic Glass (SiO2 rich)

Limonite (Ironstone Concretion)

Limonite (Hydrated iron(III) oxide-hydroxide, mixtures of FeO(OH)·nH2O)

Limonite (with Pyrite)

Limonite (Hydrated Iron Oxide) - FeO(OH)·nH2O

Mahogany Obsidian

Volcanic Glass (predominantly SiO2 with Fe2O3 inclusions)

Obsidian

Obsidian (Volcanic Glass), primarily SiO2 (Silicon Dioxide)

Obsidian

Volcanic Glass (predominantly SiO2, approximately 70% or more)

Mahogany Obsidian

Volcanic glass containing Magnetite/Hematite

Mahogany Obsidian

Obsidian (SiO2 + Fe2O3)

Limonite (Iron Ore)

Hydrous ferric oxides (FeO(OH)·nH2O)

Pearl (Biogenic Mineral)

Calcium Carbonate (primarily Aragonite) with Conchiolin; CaCO3

Snowflake Obsidian

Spherulitic Volcanic Glass (SiO2 + impurities)

Limonite Concretion

Hydrated iron(III) oxide-hydroxide (FeO(OH)·nH2O)

Obsidian

Volcanic Glass (predominantly SiO2)

Obsidian

Volcanic Glass (Silicon Dioxide with impurities)

Mahogany Obsidian

Volcanic Glass with Hematite/Magnetite (SiO2 + Fe2O3)

Amber

Succinite (with a generalized formula of C10H16O)

Obsidian

Obsidian (Amorphous volcanic glass, SiO2 with impurities)