Metamorphic Or Igneous Alteration

Weathered granite or granitic gneiss

Granite; primarily quartz, feldspar, and mica, with possible iron-oxide weathering

Serpentinite (likely)

Serpentinite, dominated by serpentine-group minerals (antigorite, lizardite, chrysotile), commonly with magnetite and minor chlorite/talc

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

Weathered quartz-rich pebble, possibly granite or granodiorite

Felsic intrusive rock; chiefly quartz, feldspar, and minor mica/amphibole

Rhodonite

Rhodonite (Mn2+SiO3 or (Mn,Fe,Mg,Ca)SiO3)

Chrysotile Asbestos

Mg3Si2O5(OH)4

Yellow Sapphire

Corundum (Al2O3:Fe)

Weathered quartz-rich rock, possibly granite or quartzite

Indeterminate; likely quartz (SiO₂) with feldspar and minor dark minerals

Diamond and Sapphire

Carbon (Diamond, C) and Aluminum Oxide (Sapphire, Al2O3)

Blue Sapphire

Corundum (Al2O3 with trace Titanium/Iron)

Quartz with Epidote

Silicon Dioxide (SiO2) with Calcium Aluminum Iron Silicate [Ca2(Al,Fe)3(SiO4)3(OH)]

Small rounded mineral pebble, possibly feldspar or quartz

Uncertain from image; likely a quartz- or feldspar-rich grain

Prehnite

Prehnite, Ca2Al2Si3O10(OH)2

Quartz pebble

Silicon dioxide (SiO2)

Black Sapphire (Basaltic Blue Sapphire)

Corundum (Al2O3)

Unakite (likely epidote–feldspar rock)

Epidote–K-feldspar–quartz aggregate; commonly approximated as pink orthoclase/microcline + green epidote + quartz

Quartz Vein in Host Rock

Silicon Dioxide (SiO2) with host rock (often Schist or Basalt)

White Quartz (Milky Quartz)

Silicon Dioxide (SiO2)

Quartz (Milky Quartz with Iron Staining)

Silicon Dioxide (SiO2)

Porphyritic Andesite or Basalt

Porphyritic Intermediate/Mafic Igneous Rock

Epidote in Granite Gneiss

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

Rounded gray river pebble, likely granite or gneiss

Indeterminate granitic rock; commonly quartz + feldspar + mica, possibly gneissic

Milky Quartz with Chlorite/Moss Infusions

Silicon Dioxide (SiO2)

Emerald

Beryl (Be3Al2(SiO3)6) with Chromium/Vanadium impurities

Blue faceted gemstone, likely synthetic sapphire or blue spinel

Corundum (Al₂O₃) if sapphire; alternatively magnesium aluminate spinel (MgAl₂O₄)

Ruby (Pink to Red Corundum)

Al2O3 (Corundum with Chromium impurities)

Blue slag-like mineral specimen, possibly bornite or chalcopyrite

Tentatively bornite (Cu5FeS4) or iridescent chalcopyrite (CuFeS2)

Pyrite on Quartz

Iron Sulfide (FeS2) on Silicon Dioxide (SiO2)

Weathered quartz-bearing rock, possibly granitic gneiss

Quartz–feldspar–mica aggregate; exact identification requires testing

Milky Quartz

Silicon Dioxide (SiO2)

Quartz crystal with Pyrite inclusions

Silicon Dioxide (SiO2) with Iron Sulfide (FeS2)

Soapstone Figurine

Steatite

Epidosite (Epidote-rich rock)

Epidosite (consisting primarily of Epidote: {Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH))

Milky Quartz with Iron Staining

Silicon Dioxide (SiO2)

Purple cabochon gemstone, likely amethyst or purple sapphire/spinel

Indeterminate from image; possible quartz (SiO₂), corundum (Al₂O₃), or spinel (MgAl₂O₄)

Epidote

Epidote; Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

Magnetite

Magnetite (Fe3O4)

Parti Sapphire

Corundum (Al2O3)

Quartz Vein in Host Rock

Silicon Dioxide (SiO2)

Quartzite with Epidote

Quartzite with Epidote inclusions

Quartz / Calcite Vein Rock

Silicon Dioxide (SiO2) or Calcium Carbonate (CaCO3)

Fuchsite in Quartz

K(Al,Cr)2(AlSi3O10)(OH)2 in SiO2