Coal (Anthracite or Bituminous)
Carbon (C) with varying hydrocarbon and mineral impurities
sedimentary
Category
Sedimentary Or Metamorphic (Low Grade)
Browse sedimentary or metamorphic (low grade) specimens identified by the Rock Identifier community.
Learn about Sedimentary Or Metamorphic (Low Grade) in the encyclopedia
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Greenstone
Greenschist / Greenstone (Epimetamorphic Rock)
metamorphic
Khondalite
Garnet-Sillimanite-Graphite Gneiss
metamorphic
Jadeite Jade
Sodium Aluminum Silicate (NaAlSi2O6)
metamorphic
Nephrite Jade
Ca2(Mg, Fe)5Si8O22(OH)2
metamorphic
Serpentine (Serpentinite)
Hydrous magnesium iron silicate, (Mg,Fe)3Si2O5(OH)4
metamorphic
Ruby (Corundum)
Corundum (Aluminum Oxide) with chromium trace elements, Al2O3
mineral
Jadeite
Jadeite (NaAlSi2O6)
mineral
Unakite (likely), tumbled specimens
Unakite: epidote + pink potassium feldspar + quartz; composition varies and may include chlorite
metamorphic
Greenstone cabochon
Likely serpentinite or chlorite-rich greenschist; exact identification requires testing
metamorphic
Likely banded slate or phyllite fragment
Slate/phyllite; chiefly fine-grained mica, quartz, and chlorite
metamorphic
Serpentinite
Serpentinite (Mg, Fe, Ni, Al, Zn, Mn)2-3(Si, Al, Fe)2O5(OH)4
metamorphic
Sapphire
Corundum (Al2O3)
gemstone
Biotite-rich schist (probable mica schist)
Mica schist; predominantly quartz, biotite, and feldspar
metamorphic
Slate
Slate; fine-grained metamorphosed shale, chiefly quartz, mica, and clay minerals
metamorphic
Dark gray metamorphic rock, likely slate or phyllite
Fine-grained foliated pelite; commonly mica- and chlorite-rich, with quartz and feldspar
metamorphic
Serpentine / Serpentinite (with Weathering Crust)
Serpentinite (Mg,Fe,Ni,Al,Zn,Mn)2-3(Si,Al,Fe)2O5(OH)4
metamorphic
Limonite (Ochreous Sandstone)
Hydrous ferric oxides (FeO(OH)qnH2O)
sedimentary
Siltstone River Rock
Siltstone (composed of silt-sized particles, silicate minerals)
sedimentary
Schist
Mica Schist (primarily Muscovite and Biotite)
metamorphic
Milky Quartz with Iron Staining
Silicon Dioxide (SiO2)
mineral
Milky Quartz
Silicon Dioxide (SiO2)
mineral
Gossan (Iron Hat)
Limonitic Gossan (Fe-oxide/hydroxide complex)
igneous
Amazonite
Microcline Feldspar (KAlSi3O8)
mineral
Tiger's Eye
Quartz pseudomorph after Crocidolite (SiO2 with Fe oxide inclusions)
mineral
Epidote
Epidote (formula: Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH))
mineral
Conglomerate
Conglomerate (clastic sedimentary rock)
sedimentary
Milky quartz (likely quartz fragment)
Quartz, silicon dioxide (SiO₂)
mineral
Serpentinite
Serpentinite (composed primarily of Serpentine group minerals, Mg3Si2O5(OH)4)
metamorphic
Greenstone (Rough Jadeite or Nephrite)
Sodium aluminum silicate (Jadeite) / Calcium magnesium iron silicate (Nephrite)
metamorphic
Likely weathered greenstone
Metabasalt (greenstone), composed chiefly of chlorite, actinolite, epidote, and albite
metamorphic
White quartz-rich rock, possibly milky quartz
Quartz (SiO₂), possibly quartzite or calcite-bearing material
mineral
Possible shale or slate fragment
Fine-grained clay-rich rock; possibly slate (low-grade metamorphosed shale)
metamorphic
Emerald in Matrix
Beryl (Be3Al2Si6O18) with Chromium/Vanadium impurities
gemstone
Limonite (Iron Stone Concretion)
Limonite (Hydrous Iron Oxide) - FeO(OH)·nH2O
mineral
Polished tiger’s-eye
Chatoyant quartz (microcrystalline quartz, SiO₂, with fibrous riebeckite/crocidolite pseudomorphs)
metamorphic
Bituminous coal
Coal, predominantly carbon with macerals and minor clay/pyrite minerals
sedimentary
Dragon Blood Jasper
Quartz (SiO2) with Epidote and Piedmontite inclusions
sedimentary
Red Jasper
Red Jasper (SiO2 with Hematite impurities)
sedimentary
Coal (Bituminous)
Bituminous Coal (C)
sedimentary
Jade (Nephrite or Jadeite)
Nephrite: Ca2(Mg,Fe)5Si8O22(OH)2; Jadeite: NaAlSi2O6
metamorphic
Greenschist
Greenschist (chlorite-epidote schist)
metamorphic