Metamorphic Or Sedimentary Depending On Local Grade

Greenstone Celt (Polished Stone Axe)

Metamorphosed mafic rock (often Basalt or Diabase)

Weathered gray metamorphic rock, likely slate or phyllite

Foliated metapelite; composition commonly quartz, mica, and chlorite

Blue-green amphibolite (likely hornblende schist)

Amphibolite dominated by hornblende amphibole and plagioclase feldspar, with possible epidote/chlorite and magnetite

Likely slate or fine-grained metamorphic rock

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

Ironstone Concretion

Siderite or Hematite Concretion

Dark gray metamorphic pebble, likely slate or phyllite

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

Bacan Stone (Chrysocolla-in-Chalcedony)

Chrysocolla in Chalcedony (SiO2 with (Cu, Al)2H2Si2O5(OH)4·nH2O)

Green Aventurine

Aventurine Quartz (SiO2 with fuchsite inclusions)

Fossiliferous Sandstone Pebble (with Crinoid / Shell Impression)

Sandstone containing fossiliferous inclusions (SiO2 matrix with calcite/silica cast fossil)

Greenstone / Serpentinite

Serpentine-group / Altered Mafic Rock

Gneiss (probable banded metamorphic rock)

Banded gneiss; typically quartz–feldspar–mica assemblage

Graphite-bearing schist (probable)

Graphite schist; chiefly quartz, mica, and graphite

Beach sandstone or cemented beachrock fragment

Lithified carbonate- or silica-rich sand; commonly calcarenite or quartz sandstone

Emerald

Beryl (Be3Al2(SiO3)6)

Quartz-veined Sandstone Pebble

Quartzite-veined Arenite

Milky quartz

Quartz (silicon dioxide, SiO₂)

Weathered sandstone pebble

Quartz-rich sandstone, likely ferruginous sandstone

Tourmaline crystal

Tourmaline Group (Complex Borosilicate)

Schist

Mica Schist

Small rounded pebble, likely porous volcanic rock

Possibly vesicular basalt or scoria; exact identification is not possible from the image alone

Mica Schist

Mica Schist

Milky Quartz with Talc / Serpentine

Silicon Dioxide (SiO2) with Mg3Si4O10(OH)2

Gneiss

Foliated quartz–feldspar–mica gneiss

Likely slate or fine-grained metamorphic rock

Slate; predominantly microcrystalline quartz, mica, and clay minerals

Marble

Metamorphosed Limestone / Calcite or Dolomite

Greenstone (likely altered basalt or serpentinite)

Chlorite-rich metabasalt or serpentinite; exact identification requires testing

Puddingstone

Conglomerate

Greenish Metamorphic Rock (likely containing epidote or chlorite)

Metamorphic rock, possibly epidosite or greenstone

Kyanite

Kyanite (Al2SiO5)

Zoisite with Hornblende

Zoisite (Ca2Al3(SiO4)3(OH)) with Amphibole inclusions

Weathered quartz-rich rock, likely quartzite

Quartzite (mostly crystalline SiO₂), tentative identification

Slate and shale outcrop

Slate: very low-grade metamorphosed shale, chiefly clay minerals, muscovite/illite, and quartz; associated shale may be present.

Greenstone (likely chlorite-rich metamorphic rock)

Chlorite-bearing greenschist; exact identification requires testing

Greenstone / Greenschist

Greenschist (composed of Chlorite, Epidote, Actinolite)

Small tumbled quartz pebble, possibly chalcedony

Quartz (SiO₂), likely microcrystalline chalcedony

Quartz (Bull Quartz)

Silicon Dioxide (SiO2)

Basalt

Mafic Volcanic Rock (composed of plagioclase, pyroxene, and olivine)

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

Mixed river-worn rock collection

Uncertain; likely quartzite, sandstone, basalt, and weathered granite or gneiss

Slate

Foliated low-grade metamorphic rock

Schist

Schist

Quartzite Cobble

Quartzite (SiO2)