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Minerals tarnishing in a short time

The following are recognized as tarnishing mechanisms at ambient condition: Oxidation, Phase transition, Light exposure, Hydration, and Dehydration.

• Aguilarite: Light gray => Dark gray
• Aikinite: Dark gray => Copper red - Iridescent
• Alabandite: Sub-Metallic => Dull luster
• Allanite-(Y): Resinous => Dull luster
• Altaite: Silver white => Yellowish brown, Blue
• Ankerite: Pale brown => Dark brown (by weathering)
• Anyuite: Silver gray => Lead gray
• Argentopyrite: Brown => Light gray
• Argyrodite: Reddish gray => Yellow, Black
• Arsenic: Silver white => Dark gray-Black, Dull luster
• Arsenolamprite: Silver white => Black, Dull luster
• Arsenopyrite: Silver white => Yellow
• Aurostibite: White => Iridescent gray

• Baumhauerite: Dark gray => Iridescent
• Benjaminite: Gray => Dull gray, Yellow, Reddish brown
• Beraunite: Dark brown-Green => Red (by oxdation)
• Berthierite: Dark gray => Iridescent
• Bieberite: Pink, Red => Dull luster (by dehydration)
• Bismuth: Pinkish silver white => Reddish brown
• Bismuthinite: Lead gray => Yellow, Iridescent
• Bohdanowiczite: Pale yellow, Pink => Yellow
• Bornite: Copper red-Iron black => Iridescent purple
• Bustamite: Pink => Pale brown

• Canfieldite: Reddish steel gray => Bluish to purplish black
• Cannizzarite: White-Silver gray => Iridescent
• Carrollite: Light gray-Steel gray => Reddish brown
• Chalcocite: Lead gray => Blue
• Chalcopyrite: Greenish yellow => Iridescent
• Chalcostibite: Lead gray-Iron black => Blue, Green
• Chlorargyrite: Colorless-Pale green => Dark purple (by light exposure)
• Cobaltite: Silver white => Dark gray
• Columbite-(Fe): Black => Iridescent
• Copper: Copper brown => Black, Green

• Digenite: Dark gray => Bluish black
• Dolomite: Colorless, White => Pale brown (Fe-bearing dolomite)
• Dyscrasite: Silver white => Yellow-Black

• Empressite: Reddish brown => Dark reddish brown
• Enargite: Grayish black => Dull black
• Eosphorite: Pale brown => Dark brown-Black (by weathering)
• Ettringite: Colorless => Whitek (by hydration)

• Ferro-gedrite: Greenish gray, Brown, Bluish green => Yellowish brown (by weathering)

• Galenobismutite: Light gray => Yellow, Iridescent
• Germanite: Reddish gray => Dark brown
• Getchellite: Dark red => Greenish-Purplish iridescent
• Graftonite: Reddish brown => Dark brown
• Greigite: Pink => Blue

• Hauchecornite: Pale yellowish brown => Dark brown
• Hauerite: Reddish brown, Brownish gray => Black
• Hedleyite: Silver white => Black
• Hessite: Lead gray => Black
• Hydrotungstite: Dark green => Yellow

• Ilesite: Green => White (by dehydration)
• Ilsemannite: Black => Blue (by light exposure)
• Inesite: Pink => Brown (by weathering)
• Inyoite: Colorless => White (by dehydration)

• Jamesonite: Grayish black => Iridescent
• Johannsenite: Bluish green, Grayish white => Brown
• Joséite (Joseite): Silver white => Dark gray
• Joséite-B (Joseite-B): Silver white => Dark gray

• Laumontite: Colorless, Pale red => White (by dehydration in the air)
• Lawrencite: White => Green-Brown (by oxidation)
• Linnaeite: Gray => Reddish brown-Purple
• Luzonite: Dark pinkish brown => Dark gray

• Magnesite: Colorless, White => Grayish brown
• Magnesite: Colorless, White => Grayish brown
• Manganosite: Green => Brown-Black (Readily by oxidation)
• Marcasite: Light gray => Yellow
• Maucherite: Reddish silver => Dark reddish gray
• Mckinstryite: Dark gray => Grayish black-Black
• Melanterite: Colorless, Pale green => Pale yellow (by hydration)
• Mendozite: Colorless => White (by dehydration)
• Millerite: Pale yellow => Iridescent, Greenish gray
• Monohydrocalcite: Colorless => White (by dehydration)
• Mooihoekite: Yellow => Dark purple, Brown

• Nickeline: Copper red => Dark gray, Black
• Nickelskutterudite: Light gray => Iridescent, Gray
• Nuffieldite: Gray => Grayish green, Reddish brown

• Owyheeite: Light gray, Silver white => Yellow

• Pararammelsbergite: Silver white => White
• Parasymplesite: Pale green => Dark green (by photo-oxidation)
• Petzite: Light gray, Black => Purple
• Pharmacosiderite: Green, Yellowish green, Brown => Red (by NH₃aq)
• Polydymite: Light gray, Dark gray => Reddish brown-Purple
• Proustite: Red => Black (by light exposure)
• Pyrargyrite: Red => Black (by light exposure)
• Pyrochroite: Colorless, Pale blue => Brown-Black (Readily by oxidation)

• Rajite: Resinous => Dull luster
• Reddingite: Colorless, Pale pink, Pale yellow => Dark brown
• Renierite: Orange, Yellowish brown => Reddish brown
• Rickardite: Reddish purple => Dark red
• Rockbridgeite: Dark green, Grayish green, Yellowish brown => Brown (by oxidation)
• Rowlandite-(Y): Pale green, Colorless, Vitreous luster => Brownish red, Waxy luster

• Safflorite: Silver white => Dark gray
• Sarcopside: Colorless => Brown
• Siderite: Yellow, Brown => Dark brown, Black (Mn-bearing siderite)
• Silver: Silver white => Black (by sulfurization)
• Skutterudite: Light gray, Silver white => Gray
• Stannite: Greenish gray, Black => Bluish gray
• Stannoidite: Yellowish brown, Metallic luster => Dull luster
• Sternbergite: Yellowish brown => Bluish purple
• Stibnite: Light gray with a blue tint => Dark gray
• Stromeyerite: Dark gray => Dark blue, Bluish gray
• Stützite (Stutzite): Dark gray, Brown => Iridescent
• Sylvanite: Silver white, Pale yellow => Dark gray
• Symplesite: Pale green, Blue => Greenish black (by photo-oxidation), Brown (by KOH or H₂O₂)

• Talnakhite: Yellowish brown => Pink, Brown
• Tanohataite: Pale pink => Black
• Teallite: Gray, Dark gray => Dull luster or Iridescent
• Tetradymite: Dark gray, Silver white => Iridescent
• Tetrahedrite: Dark gray, Grayish black => Black with a blue tint
• Triphylite: Greenish brown, Greenish gray => Black
• Troilite: Grayish brown => Yellowish brown
• Tyuyamunite: Yellow => Greenish yellow (by light exposure)

• Variscite: Pale green, Pale blue, Colorless => Blue, Purple (by heating)
• Violarite: Violet gray, Gray => Reddish brown, Purple

• Warwickite: Dark brown, Grayiolet gray, Gray => Dull black, Yellow (by weathering)
• Weissite: Bluish black => Black

• Yarrowite: Bluish black => Black