Metamorphic (Low Grade)

Greenstone

Metabasalt / Chlorite-actinolite-epidote schist

Epidosite

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

Black slate

Slate, a fine-grained metamorphic rock composed mainly of mica-group minerals, chlorite, and quartz

Serpentine / Serpentinite (with Weathering Crust)

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

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

Schist

Mica Schist (primarily Muscovite and Biotite)

Sapphire

Corundum (Al2O3)

Limonite (Iron Ore)

FeO(OH)·nH2O (Hydrous ferric oxide)

Tumbled green aventurine quartz

Aventurine quartz; microcrystalline SiO₂ with dispersed mica or fuchsite inclusions

Serpentine (Serpentinite)

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

Black Onyx

Silicon Dioxide (SiO2) - Chalcedony variety

Ruby (Corundum)

Corundum (Aluminum Oxide) with chromium trace elements, Al2O3

Banded gneiss

Gneiss, commonly quartz–feldspar–mica gneiss

Serpentinite

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

Slate

Metamorphic Pelitic Rock

Likely weathered greenstone

Metabasalt (greenstone), composed chiefly of chlorite, actinolite, epidote, and albite

Chert / Quartzite

Silicon Dioxide (SiO2)

Jadeite Jade

Sodium Aluminum Silicate (NaAlSi2O6)

Pyrite

Iron Sulfide (FeS2)

Nephrite Jade

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

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

Anthracite Coal

Anthracite (Carbon-based sedimentary-derived metamorphic rock)

Rough emerald

Emerald, green variety of beryl (Be₃Al₂Si₆O₁₈), colored mainly by chromium and/or vanadium

Greenstone pebble

Greenschist-facies mafic rock, commonly derived from basalt; likely rich in chlorite, actinolite, and epidote

Weathered quartz-rich pebble, likely sandstone or quartzite

Quartzite (SiO₂), possibly ferruginous sandstone

Jadeite

Jadeite (NaAlSi2O6)

Emerald in Matrix

Beryl (Be3Al2Si6O18) with Chromium/Vanadium impurities

Milky Quartz with Iron Staining

Silicon Dioxide (SiO2)

Milky Quartz

Silicon Dioxide (SiO2)

Gossan (Iron Hat)

Limonitic Gossan (Fe-oxide/hydroxide complex)

Citrine

Silicon Dioxide (Quartz variety, SiO2)

Greenstone (Rough Jadeite or Nephrite)

Sodium aluminum silicate (Jadeite) / Calcium magnesium iron silicate (Nephrite)

Greenstone / Glauconitic Siltstone

Metabasalt or Glauconite-rich Sedimentary Rock

Milky quartz (likely quartz fragment)

Quartz, silicon dioxide (SiO₂)

White quartz-rich rock, possibly milky quartz

Quartz (SiO₂), possibly quartzite or calcite-bearing material

Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

Weathered metamorphic rock, likely chlorite schist or greenstone

Chlorite-rich schist/greenschist; exact identification requires testing

Greenschist

Greenschist (chlorite-epidote schist)