Mineral Like Biological Tissue

Fluorite (left), Sodalite (middle), Dumortierite/Tumbled Quartzite (right)

Calcium Fluoride (CaF2), Sodium Aluminum Silicate Chloride (Na8(Al6Si6O24)Cl2), Aluminum Borosilicate (Al7(BO3)(SiO4)3O3)

Green Fluorite

Calcium Fluoride (CaF2)

Amethyst (Tumbled)

Amethyst (Silicon Dioxide, SiO2 + Fe4+)

Sandstone with Secondary Mineral Encrustation

Arenite with Silica/Calcite deposits (SiO2 or CaCO3)

Obsidian

Volcanic glass (SiO2 - Silicon Dioxide with impurities)

Carnelian

Carnelian Agate (SiO2)

Druzy Quartz

Silicon Dioxide (SiO2)

Echinoid Fossil (Commonly called a Sea Urchin or Heart Urchin)

Phylum Echinodermata, Class Echinoidea

Mica Schist

Mica Schist (contains Muscovite/Biotite, Quartz)

Rutilated Quartz (beads)

SiO2 with TiO2 inclusions (Titanium Dioxide inclusions within Quartz)

Milky Quartz with Iron Staining

Quartz (Silicon Dioxide) - SiO2

Native Copper

Native Copper (Cu)

Moss Agate

SiO2 (Silicon Dioxide) with dendritic inclusions

Sandstone (Quartzose Sandstone)

Clastic Sedimentary Rock (Lithic arenite / Quartz arenite)

Fossilized Wood (with Coal and Limonite)

Petrified Wood (Silicified or Carbonized Flora)

Muscovite Mica

Muscovite (KAl2(AlSi3O10)(OH)2)

Muscovite Mica (Golden/Yellow variety)

KAl2(AlSi3O10)(F,OH)2

Amygdaloidal Rhyolite (often called Lake Superior Agate relative)

Rhyolite with Calcite/Quartz amygdules (SiO2 and secondary minerals)

Limonite (Iron Ore)

Limonite (Iron oxide-hydroxide mixture, FeO(OH)·nH2O)

Magnetite Sand (Black Sand)

Magnetite (Fe3O4)

Eclogite

Eclogite (Omphacite + Pyrope)

Diorite

Diorite (Intermediate intrusive igneous rock)

Amygdaloidal Basalt

Amygdaloidal Basalt (containing secondary minerals like Quartz, Zeolites, or Calcite)

Biotite / Black Mica

Biotite K(Mg,Fe)3AlSi3O10(F,OH)2

Turquoise

Turquoise (Hydrated phosphate of copper and aluminium), CuAl6(PO4)4(OH)8·4H2O

Schist

Mica Schist

Black Obsidian

Volcanic Glass (SiO2)

Dendritic Opal

Hydrated Silica (SiO2·nH2O) with Manganese or Iron Oxide inclusions

Orthoclase Feldspar

Orthoclase (KAlSi3O8)

Clear Quartz Crystal (Herkimer Diamond style)

Silicon Dioxide (SiO2)

Quartz Geode (partially opened)

Silicon Dioxide (SiO2) with iron staining

Schist (Micaceous)

Mica Schist

Quartz Geode

Silicon Dioxide (SiO2)

Schist

Schist (metamorphic rock)

Schist (specifically Mica Schist)

Mica Schist (primarily composed of Muscovite KAl2(AlSi3O10)(OH)2 and Biotite)

Prehnite

Prehnite (Ca2Al2Si3O10(OH)2)

Clear Quartz (Tumbled)

Quartz (Silicon Dioxide - SiO2)

Limonite Sandstone

Ferruginous Sandstone (Hydrated Iron Oxide)

Sandstone (likely Quartzose Sandstone pebble)

Arenite (primarily SiO2)

Tree Agate

Dendritic Agate (Silicon Dioxide, SiO2)

Yellow Ochre / Limonite

Limonite (FeO(OH)·nH2O)

Limonite (Ironstone)

Hydrated Iron Oxide (FeO(OH)·nH2O)