Mineral Pseudomorph

Aventurine

Aventurine Quartz (SiO2 with inclusions)

Shale

Shale (comprised mostly of clay minerals and quartz)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Milky Quartz Pebble

Quartz (Silicon Dioxide, SiO2)

Schist (Micaceous Schist)

Schist (comprising Muscovite/Biotite mica, Quartz, and Feldspar)

Milky Quartz

Silicon Dioxide (SiO2)

Milky Quartz with Iron Staining and Matrix

Silicon Dioxide (SiO2)

Pyrite in Quartzite/Graphite Matrix

Iron Sulfide (FeS2)

Ironstone with Pyrite

Ferruginous Sandstone (Fe2O3) with minor Sulfide minerals (FeS2)

Pink Lepidolite

Lepidolite (K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2)

Schist

Mica Schist (primarily Muscovite and Biotite)

Diorite

Diorite (Intermediate intrusive igneous rock)

Native Sulfur

Sulfur (S8)

Red Sandstone

Arenite (with Iron Oxide / Hematite cementation)

Greenstone / Diabase Porphyry

Porphyritic Diabase (Micro-gabbro)

Fossilized Sand Tiger Shark Tooth

Carcharias taurus / Striatolamia macrota (mineralized as Hydroxylapatite/Francolite)

Concretion

Various mineral compositions, typically carbonate or iron oxide cemented sediment

Quartz / Quartzite

Silicon Dioxide (SiO2)

Jasper (Iron-stained Quartzite/Chert)

Silicon Dioxide (SiO2) with iron oxide inclusions

Pearl (nacre)

Calcium Carbonate (mostly CaCO3 as Aragonite) and Conchiolin

Fluorite

Calcium Fluoride (CaF2)

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Concretion or Geode (unbroken)

Varied (depending on mineral composition and cementing agent). For quartz-lined geodes, the scientific name of the dominant mineral would be Quartz (SiO2). For calcite-lined geodes, Calcite (CaCO3). Concretions are often composed of cryptocrystalline quartz (chert), calcite, or iron oxides.

Ferruginous Sandstone (Gozzan/Ironstone)

Arenite with Limonite/Goethite cement (FeO(OH)·nH2O)

Basalt

Mafic Igneous Rock (primarily Plagioclase and Pyroxene)

Pegmatite

Granitic Pegmatite

Epidote

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

Pyrite

Iron Disulfide (FeS2)

Sandstone

Arenite (composed mainly of SiO2)

Rose Quartz

Silicon Dioxide (SiO2) with trace amounts of titanium, iron, or manganese

Sandstone

Sandstone (Sedimentary rock composed of silicate grains)

Pyrite (Fool's Gold)

Iron Sulfide (FeS2)

Pyrite

Iron Sulfide (FeS2)

Sandstone

Arenite (SiO2 predominantly)

Amber

Succinite (fossilized tree resin), C10H16O

Pink Lepidolite

Lepidolite (K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2)

Schist

Schist (Crystalline metamorphic rock)

Gneiss

Gneiss

Quartzite

Quartzite (SiO2)

Amygdaloidal Basalt

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