Metamorphic (Low Grade)

Greenstone / Graywacke

Metagraywacke or Chlorite Schist

Pyrite in Slate

Iron Sulfide (FeS2) in Slate host matrix

Tumbled greenstone/chlorite-rich pebble

Likely chlorite-rich greenschist or altered basalt; exact identification requires testing

Polished tiger’s-eye cabochon (probable)

Quartz variety, SiO₂, with fibrous riebeckite/crocidolite-derived inclusions

Likely slate fragments

Slate, a fine-grained metamorphic rock composed chiefly of quartz, mica, and chlorite

Biotite-rich schist (probable mica schist)

Mica schist; predominantly quartz, biotite, and feldspar

Greenstone pebble

Greenstone (metamorphosed mafic rock, commonly altered basalt); exact identification requires testing

Weathered slate or phyllite

Foliated metamorphic rock, commonly quartz–mica–chlorite assemblage

Greenstone with rusty mineral patches

Greenstone (metamorphosed mafic volcanic rock; likely chlorite–epidote–actinolite assemblage)

Tumbled tiger’s-eye

Quartz variety with fibrous crocidolite pseudomorphs; SiO₂

Unakite (likely)

Epidote–orthoclase–quartz rock; composition approximately epidote Ca₂(Al,Fe³⁺)₃(SiO₄)₃(OH) plus K-feldspar and quartz

Veined marble or calcitic limestone

Calcite-dominant carbonate rock (CaCO₃), likely marble

Slate

Slate; predominantly fine-grained mica- and clay-mineral rock, commonly derived from shale

Dark metamorphic rock, likely slate or phyllite

Fine-grained foliated metamorphic rock; commonly dominated by quartz, mica, and chlorite

Polished banded stone, likely tiger’s-eye

Tiger’s-eye quartz (fibrous chalcedony/quartz, SiO₂), possibly iron-rich quartzite

Greenstone (Chert)

Microcrystalline Silica (SiO2) with chlorite/epidote inclusions

Soapstone (steatite), possibly talc-rich schist

Steatite; predominantly talc, Mg₃Si₄O₁₀(OH)₂, with possible chlorite, mica, and carbonates

Engraved polished dark stone (likely slate or basalt)

Probable fine-grained slate (microcrystalline phyllosilicates), possibly basalt; exact identification requires testing

Greenstone Celt (Polished Stone Axe)

Metamorphosed mafic rock (often Basalt or Diabase)

Anthracite Coal

Anthracite

Epidote with Quartz and Feldspar

Ca2(Al2,Fe3+)(SiO4)3(OH) (Epidote complex)

Slate

Slate; fine-grained foliated metamorphic rock, commonly derived from shale or mudstone

Tumbled ruby or ruby-bearing corundum

Corundum (Al₂O₃), red variety colored mainly by chromium

Weathered metamorphic rock, likely schist or slate

Foliated pelitic metamorphic rock; commonly muscovite–chlorite schist or phyllite

Jadeite

NaAl(Si2O6)

Sapphire (Blue/Violet Rough)

Corundum (Al2O3)

Green Schist

Greenschist (composed primarily of Chlorite, Actinolite, and Epidote)

Pyrite

Iron Disulfide (FeS2)

Tumbled milky quartz

Quartz (SiO₂), microcrystalline or massive variety

Serpentinite (likely)

Serpentinite; chiefly serpentine-group minerals, Mg₃Si₂O₅(OH)₄, commonly with magnetite and minor carbonates

Quartz / Quartzite

Silicon Dioxide (SiO2)

Tumbled greenstone, likely serpentine or altered basalt

Serpentine-group minerals, chiefly Mg₃Si₂O₅(OH)₄; possibly chlorite/epidote-bearing mafic rock

Milky Quartz

Quartz (Silicon Dioxide, SiO2)

Prehnite

Calcium aluminum silicate hydroxide, Ca2Al2Si3O10(OH)2

Rounded, striated pebble—likely slate or fine-grained metamorphic rock

Slate/phyllite; predominantly quartz, mica, and clay-derived minerals

Banded Slate (Sedimentary Pebble)

Slate (Metamorphosed Shale or Mudstone)

Tumbled ruby-bearing corundum

Corundum (Al₂O₃), likely ruby variety

Fine-grained dark metamorphic rock, likely slate or phyllite

Slate/phyllite, composed mainly of mica-group minerals, quartz, and clay-derived minerals

Epidote with Magnetite/Hematite inclusions

Epidote (Ca2(Al2,Fe3+)(SiO4)3(OH)) with Iron Oxides

Rough Emerald

Beryl (Be3Al2Si6O18 with Chromium/Vanadium impurities)

Jadeite Jade

Jadeite (NaAlSi2O6)

Likely fine-grained greenstone

Greenstone, typically metamorphosed mafic volcanic rock (metabasalt; commonly chlorite- and actinolite-bearing)