Limonite Geode / Ironstone Concretion
Hydrated iron oxide-hydroxide (FeO(OH)·n H2O)
sedimentary
Category
Mineral (Extraterrestrial)
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Quartz Pebble
Silicon Dioxide (SiO2)
sedimentary
Quartz Pebble
Silicon Dioxide (SiO2)
sedimentary
Limonite Concretion
Goethite/Limonite concretion (FeO(OH)·nH2O)
sedimentary
Quartz Pebble
Quartz (Silicon Dioxide, SiO2)
sedimentary
Quartz Pebble
Silicon Dioxide (SiO2)
sedimentary
Limonite (Ironstone) pseudomorph
Limonite (Hydrous ferric oxide), FeO(OH)·nH2O
mineral
Fluorite on Matrix
Calcium Fluoride (CaF2)
mineral
Unidentified gray rock/mineral specimen
Indeterminate; possibly quartz-rich rock or a metallic sulfide-bearing specimen
mineral
Banded gneiss pebble
Gneiss, composed chiefly of quartz, feldspar, and mica/amphibole
metamorphic
Galena
Lead sulfide (PbS)
mineral
Sandstone
Clastic Sedimentary Rock
sedimentary
Note regarding baguette production (not a rock)
Digital text image - Somali language
not a rock
Small white mineral fragment
Indeterminate; possibly quartz, calcite, or feldspar
mineral
Agate / Chalcedony Geode
Silicon Dioxide (SiO2)
sedimentary
Lapis Lazuli
Lapis Lazuli (Mineral composition: Lazurite, Calcite, Sodalite, and Pyrite)
metamorphic
Potassium Feldspar (Orthoclase / Microcline)
KAlSi3O8 (Potassium Aluminum Silicate)
mineral
Quartz (Druzy or Chalcedony variant)
Silicon Dioxide (SiO2)
mineral
Epidote
Epidote (Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH))
metamorphic
Epidote
{Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH)
mineral
Epidote
Epidote (Ca2(Al,Fe)3(SiO4)3(OH))
metamorphic
Epidote
Epidote ({Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH))
mineral
Gneiss (River Cobble)
Gneiss
metamorphic
Limonite on Sandstone
Iron Oxyhydroxide (FeO(OH)·nH2O) on Quartz Sandstone
sedimentary
Limonite / Goethite (Ironstone Nodule)
Hydrated Iron(III) Oxide-Hydroxide (FeO(OH)·nH2O)
mineral
Hematite
Iron Oxide (Fe2O3)
mineral
Quartz (Druzy / Crystalline)
Silicon Dioxide (SiO2)
mineral
Fluorite
Calcium Fluoride (CaF2)
mineral
Fluorite
Calcium Fluoride (CaF2)
mineral
Obsidian
Volcanic Glass (SiO2)
igneous
Snowflake Obsidian
Obsidian with Cristobalite inclusions (SiO2)
igneous
Turquoise (Dyed Howlite/Magnesite imitation)
CuAl6(PO4)4(OH)8·4H2O (Target mineral) / Ca2B5SiO9(OH)5 (Actual specimen: Howlite)
mineral
Tumbled granite or granitic gneiss pebble
Granite/granitic gneiss, chiefly quartz, feldspar, and dark biotite or amphibole
igneous
Shark Tooth Fossil
Otodus obliquus (or similar prehistoric lamniform shark tooth)
fossil
Fossil Shark Tooth
Chondrichthyes (class)
fossil
Fossilized Shell Fragment
Bivalvia or Gastropoda (Class) fragment
fossil
Chakra Crystal Bracelet
Mixed Mineral Assortment
gemstone
River Stone (likely Basalt or Greywacke)
Basalt with mineral veining
igneous
Milky Quartz with Algae/Chlorite
Silicon Dioxide (SiO2)
mineral
Sandstone
Arenite (SiO2 based)
sedimentary
Limonite (Ironstone)
Limonite (FeOO·nH2O)
mineral
Quartz Geode Fragment
Silicon Dioxide (SiO2)
sedimentary