Mineral (Specifically A Mineraloid)

Pyrite in Matrix (Fool's Gold)

Iron Sulfide (FeS2)

Erythrite in Cobaltite Ore

Erythrite (Co3(AsO4)2·8H2O) with Cobaltite (CoAsS)

Turquoise (possible Howlite imitation)

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

Quartz Geode

Quartz (Silicon Dioxide, SiO2) in a Geode

Banded Agate

Agate (Silicon Dioxide - SiO2)

Pyrite

Iron Sulfide (FeS2)

Limonite with Gold-bearing Quartz

Hydrated Iron Oxide Hydroxide, FeO(OH)·nH2O

Chalcopyrite

Copper Iron Sulfide (CuFeS2)

Yellow Ochre / Limonite

Hydrated ferric oxide (FeO(OH)·nH2O)

Prehnite

Prehnite, Ca2Al2Si3O10(OH)2

Limonite (Ochreous Sandstone)

Hydrous ferric oxides (FeO(OH)qnH2O)

Geode

Silicon dioxide (Quartz/Chalcedony) concretion

Magnetite or Ironstone Nodule

Magnetite (Fe3O4) or Hematite-rich Sedimentary Nodule

Selenite (Satin Spar)

Calcium Sulfate Dihydrate (CaSO4·2H2O)

Calcite

Calcium Carbonate (CaCO3)

Small pale rock fragment

Indeterminate; possibly quartz, calcite, or a weathered feldspar-rich fragment

Copper Ore (Malachite/Chrysocolla bearing)

Cupriferous rock containing secondary copper minerals like Cu2CO3(OH)2

Selenite

Gypsum (CaSO4·2H2O)

Fluorite

Calcium Fluoride (CaF2)

Diorite

Intermediate plutonic igneous rock

Vanadinite

Pb5(VO4)3Cl

Pyrite in Quartz

Iron Sulfide (FeS2) in Silicon Dioxide (SiO2)

Hematite

Iron Oxide (Fe2O3)

Howlite

Calcium borosilicate hydroxide (Ca2B5SiO9(OH)5)

Yellow Calcite

Calcium Carbonate (CaCO3)

Prehnite

Calcium aluminum silicate hydroxide, Ca2Al(AlSi3O10)(OH)2

Native Copper

Copper (Cu)

Hematite (Botryoidal / Kidney Ore)

Iron Oxide (Fe2O3)

Quartz (Iron-stained Quartz)

Silicon Dioxide (SiO2)

Rhodochrosite

Manganese Carbonate (MnCO3)

Rhodonite

Manganese Inosilicate (Mn,Fe,Mg,Ca)SiO3

Selenite (Satin Spar)

Gypsum (CaSO4·2H2O)

Selenite (Satin Spar)

Gypsum (Calcium Sulfate Dihydrate) - CaSO4·2H2O

Copper Ore with Chrysocolla/Malachite

Hydrated copper phyllosilicate (Chrysocolla) / Copper carbonate hydroxide (Malachite)

Rhodonite

Rhodonite (Mn,Fe,Mg,Ca)SiO3

Lepidolite on Pegmatite

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

Kaolinite (Kaolin)

Kaolinite (Al2Si2O5(OH)4)

Lepidolite

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

Satin Spar (Gypsum)

Calcium Sulfate Dihydrate (CaSO4·2H2O)

Arfvedsonite (often mistakenly sold as Astrophyllite)

Arfvedsonite [Na3(Fe2+)4Fe3+Si8O22(OH)2]

Sulfur (on Matrix)

Native Sulfur (S8)

Chrysocolla in Cuprite (Sonora Sunrise)

Cu2-xAlx(H2-xSi2O5)(OH)4·n(H2O) with Cu2O