Metamorphic (Low Grade)

Black shale or slate fragment

Carbonaceous shale; possibly low-grade slate (clay minerals, quartz, carbon/graphite)

Tumbled serpentine

Serpentine-group minerals, chiefly lizardite and antigorite; approximate formula Mg₃Si₂O₅(OH)₄

Polished black slate or schist slab

Slate/schist, composed mainly of fine-grained mica, quartz, and chlorite

Blue-gray metamorphic rock, likely slate or phyllite

Fine-grained foliated metapelite; commonly mica- and chlorite-rich

Polished tiger’s-eye

Quartz variety: fibrous chatoyant quartz, chiefly SiO₂, pseudomorphous after crocidolite

Greenstone (likely altered basalt or metabasalt)

Chlorite–actinolite-rich metabasalt; composition commonly dominated by chlorite, actinolite, epidote, albite, and quartz

Hard Sandstone (Quartzite)

Quartz-rich Sedimentary Rock (Proto-Quartzite)

Polished tiger’s-eye (likely blue-and-golden tiger’s-eye)

Fibrous quartz, SiO₂, pseudomorphic after crocidolite; varieties include golden tiger’s-eye and hawk’s-eye

Weathered greenstone (likely serpentinite or altered basalt)

Serpentinite-group rock, commonly dominated by serpentine minerals (antigorite/lizardite); exact identification requires testing

Crystalline limestone (marble-like calcite rock)

Calcite, CaCO₃; likely recrystallized limestone (marble)

Greenstone

Metabasalt / Chlorite-actinolite-epidote schist

Epidosite

Epidosite (predominantly Epidote {Ca2Al2Fe3+Si3O12(OH)} and Quartz {SiO2})

Black Onyx

Silicon Dioxide (SiO2) - Chalcedony variety

Ruby (Corundum)

Aluminium oxide (Al2O3) with Chromium traces

Greenstone

Greenschist / Greenstone (Epimetamorphic Rock)

Khondalite

Garnet-Sillimanite-Graphite Gneiss

Jadeite Jade

Sodium Aluminum Silicate (NaAlSi2O6)

Pyrite

Iron Sulfide (FeS2)

Chert / Quartzite

Silicon Dioxide (SiO2)

Nephrite Jade

Ca2(Mg, Fe)5Si8O22(OH)2

Serpentine (Serpentinite)

Hydrous magnesium iron silicate, (Mg,Fe)3Si2O5(OH)4

Ruby (Corundum)

Corundum (Aluminum Oxide) with chromium trace elements, Al2O3

Jadeite

Jadeite (NaAlSi2O6)

Garnet-Bearing Gneiss

Garnetiferous Feldspathic Gneiss

Unakite (likely), tumbled specimens

Unakite: epidote + pink potassium feldspar + quartz; composition varies and may include chlorite

Greenstone cabochon

Likely serpentinite or chlorite-rich greenschist; exact identification requires testing

Likely banded slate or phyllite fragment

Slate/phyllite; chiefly fine-grained mica, quartz, and chlorite

Schist (specifically Chlorite/Greenschist)

Chlorite Schist

Serpentinite

Serpentinite (Mg, Fe, Ni, Al, Zn, Mn)2-3(Si, Al, Fe)2O5(OH)4

Sapphire

Corundum (Al2O3)

Limonite (Iron Ore)

FeO(OH)·nH2O (Hydrous ferric oxide)

Biotite-rich schist (probable mica schist)

Mica schist; predominantly quartz, biotite, and feldspar

Slate

Slate; fine-grained metamorphosed shale, chiefly quartz, mica, and clay minerals

Dark gray metamorphic rock, likely slate or phyllite

Fine-grained foliated pelite; commonly mica- and chlorite-rich, with quartz and feldspar

Serpentine / Serpentinite (with Weathering Crust)

Serpentinite (Mg,Fe,Ni,Al,Zn,Mn)2-3(Si,Al,Fe)2O5(OH)4

Schist

Mica Schist (primarily Muscovite and Biotite)

Banded gneiss

Gneiss, commonly quartz–feldspar–mica gneiss

Milky Quartz with Iron Staining

Silicon Dioxide (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Gossan (Iron Hat)

Limonitic Gossan (Fe-oxide/hydroxide complex)

Slate

Metamorphic Pelitic Rock

Weathered quartz-rich pebble, likely sandstone or quartzite

Quartzite (SiO₂), possibly ferruginous sandstone