Metamorphic (Low Grade)

Siltstone / Slate

Siltstone / Low-grade Slate

Dark gray slate (possibly argillite or shale)

Slate, a low-grade metamorphic rock derived mainly from shale; composition commonly quartz, illite/muscovite, chlorite, and clay minerals

Purple-gray shale or slate fragment

Argillite/slate, chiefly compacted clay minerals with quartz and mica

Jadeite Jade

Jadeite (NaAlSi2O6)

Milky Quartz

Silicon Dioxide (SiO2)

Schist (Greenschist / Mica Schist)

Schist (variable mineral composition, commonly containing quartz, feldspar, mica, chlorite)

Emerald in Matrix (Quartz/Calcite)

Beryl (Be3Al2Si6O18) with Chromium/Vanadium impurities

Banded Jasper / Yellow Jasper with Chlorite or Epidote inclusions

Silicon Dioxide (SiO2) with iron oxide and silicate impurities

Dark gray metamorphic rock, likely slate or phyllite

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

Small polished green stone, possibly serpentine or greenstone

Likely serpentine-rich rock; exact identification is limited by the blurred image

Schist

Mica Schist

Greenstone / altered basalt (probable)

Chlorite–epidote–actinolite-rich metabasalt; exact identification requires testing

Calcite-rich limestone (likely crystalline limestone/marble)

Calcite, CaCO₃; likely recrystallized carbonate rock

Polished tiger’s-eye

Quartz variety: fibrous golden-brown chalcedonic quartz, SiO₂

Likely polished blue-gray stone, possibly labradorite or slate

Tentatively labradorite (plagioclase feldspar, NaAlSi₃O₈–CaAl₂Si₂O₈) or blue-gray slate; identification is limited by the close-up image

Foliated metamorphic rock (likely slate or phyllite)

Slate/phyllite; chiefly quartz, mica, and chlorite

Banded Chert or Unakite-like Rock

Epidotized Granulite or Jasperoid Chert

Onyx (Calcite Onyx / Mexican Onyx)

Calcium Carbonate (CaCO3)

Likely micaceous metamorphic rock fragment

Probable phyllite or mica schist; quartz–muscovite-rich assemblage

Greenstone

Metabasalt / Greenschist

Anthracite Coal

Anthracite

Greenstone

Metabasalt (often contains Chlorite, Actinolite, and Epidote)

Pietersite

Brecciated Crocidolite in Quartz (Chalcedony)

Epidote and Quartz in Basalt

Epidote [Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)] in Metabasalt

Epidote

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

Jadeite

NaAl(Si2O6)

Slate

Slate; predominantly fine-grained phyllosilicates (muscovite/illite, chlorite) with quartz and possible iron oxides

Greenschist (Chlorite Schist)

Greenschist (containing chlorite, actinolite, and epidote)

Slate

Slate; fine-grained metamorphosed shale, commonly quartz–muscovite/chlorite rich

Epidosite (Epidote-rich rock)

Epidotalite (primarily Ca2(Al2Fe3+)(SiO4)(Si2O7)O(OH))

Polished tiger’s-eye

Quartz-rich aggregate with chatoyant fibrous crocidolite pseudomorphs; mainly SiO₂

Polished tiger’s eye

Quartz variety, SiO₂, with parallel fibrous amphibole pseudomorphs (crocidolite)

Dark gray foliated metamorphic rock, likely slate or phyllite

Slate/phyllite; chiefly quartz, mica, and chlorite

Pearl and Garnet Glass

Calcium Carbonate (CaCO3) for pearl; Silicon Dioxide (SiO2) for glass

Polished greenstone pebble

Likely serpentinite or chlorite-rich greenschist

Nephrite Jade

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

Jade (likely Nephrite Jade based on appearance)

Nephrite (a variety of actinolite, Ca2(Mg,Fe)5Si8O22(OH)2)

Greenstone (Prase / Metavolcanic)

Metamorphosed volcanic rock (Greenstone)

Weathered greenish mineral specimen, possibly serpentine or epidote

Tentatively serpentine-group mineral (Mg3Si2O5(OH)4) or epidote (Ca2(Al,Fe)3Si3O12(OH)); identification is uncertain from the image alone

Weathered dark metamorphic rock, likely slate or phyllite

Fine-grained foliated rock, probably slate/phyllite; exact identification requires testing

Green Quartzite (Aventurine type)

Quartzite (principally Quartz, SiO2) with inclusions of Fuchsite

Milky quartz-rich rock

Quartz, SiO₂; possibly quartzite or massive vein quartz