Mineral (Impactite)

Rainbow Fluorite

Fluorite (Calcium Fluoride, CaF2)

Vesicular basalt (likely weathered lava rock)

Basalt; chiefly plagioclase, pyroxene, and often olivine

Mixed Gemstone and Mineral Collection

Mixed Silica and Carbonate minerals (SiO2, CaSO4·2H2O, etc.)

Carved serpentine wing sculpture

Serpentine-group rock, chiefly antigorite/lizardite: Mg3Si2O5(OH)4

Green Fluorite

Fluorite (Calcium Fluoride, CaF2)

Unidentified gray rock/mineral specimen

Indeterminate; possibly quartz-rich rock or a metallic sulfide-bearing specimen

Limonite (Iron Ore)

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

Quartz Pebble

Silicon Dioxide (SiO2)

Limonite Concretion

Goethite/Limonite concretion (FeO(OH)·nH2O)

Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Biotite-rich gneiss (probable)

Foliated quartz–feldspar–biotite gneiss; composition commonly includes quartz (SiO₂), feldspar, and biotite mica

Quartz Pebble

Silicon Dioxide (SiO2)

Limonite Geode / Ironstone Concretion

Hydrated iron oxide-hydroxide (FeO(OH)·n H2O)

Quartz Pebble

Silicon Dioxide (SiO2)

Quartz Pebble

Silicon Dioxide (SiO2)

Limonite (Ironstone) pseudomorph

Limonite (Hydrous ferric oxide), FeO(OH)·nH2O

Fluorite on Matrix

Calcium Fluoride (CaF2)

Banded gneiss pebble

Gneiss, composed chiefly of quartz, feldspar, and mica/amphibole

Small white mineral fragment

Indeterminate; possibly quartz, calcite, or feldspar

Galena

Lead sulfide (PbS)

Sandstone

Clastic Sedimentary Rock

Note regarding baguette production (not a rock)

Digital text image - Somali language

Agate / Chalcedony Geode

Silicon Dioxide (SiO2)

Limonite on Sandstone

Iron Oxyhydroxide (FeO(OH)·nH2O) on Quartz Sandstone

Potassium Feldspar (Orthoclase / Microcline)

KAlSi3O8 (Potassium Aluminum Silicate)

Quartz (Druzy or Chalcedony variant)

Silicon Dioxide (SiO2)

Gneiss (River Cobble)

Gneiss

Lapis Lazuli

Lapis Lazuli (Mineral composition: Lazurite, Calcite, Sodalite, and Pyrite)

Epidote

Epidote (Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH))

Epidote

{Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH)

Epidote

Epidote (Ca2(Al,Fe)3(SiO4)3(OH))

Epidote

Epidote ({Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH))

Hematite

Iron Oxide (Fe2O3)

Limonite / Goethite (Ironstone Nodule)

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

Fluorite

Calcium Fluoride (CaF2)

Quartz (Druzy / Crystalline)

Silicon Dioxide (SiO2)

Fluorite

Calcium Fluoride (CaF2)

Obsidian

Volcanic Glass (SiO2)

Snowflake Obsidian

Obsidian with Cristobalite inclusions (SiO2)

Turquoise (Dyed Howlite/Magnesite imitation)

CuAl6(PO4)4(OH)8·4H2O (Target mineral) / Ca2B5SiO9(OH)5 (Actual specimen: Howlite)

Tumbled granite or granitic gneiss pebble

Granite/granitic gneiss, chiefly quartz, feldspar, and dark biotite or amphibole