This is a list of sun sensitive crystals that should not be left in direct sunlight as they will fade.
Anglesite (brown to colorless)
Anhydrite (blue to colorless)
Apatite (mauve or pink to colorless)
– Pakistan, Afghanistan* pink fades
– La Marina, Mine, Pauna, Boyacá Colombia* pink fades
– Moro Vehlo Mine, Nova Lima, Minas Gerais pink fades
– Himalaya Mine, CA
Aragonite (w/ color)
Barite (colorless or blue to darker; blue to colorless; yellow/brown to green or blue)
– “Hartsel” Barite can turn from white to blue in sunlight.
– Moscona Mine barite goes from white to blue in sunlight but reversible.
Beryl v Aquamarine*
– Blue beryl can be made irradiating certain pale natural beryls but like maxime, the electron trap is shallow and so unstable. Fe-colored aquamarines are perfectly stable.
Beryl v Maxixe* (Blue to colorless or pink)
Beryl v Morganite (apricot or purplish to pink; pink to paler pink)
– One Afghanistan find, pink beryl turned deep yellow with a few hours of sunlight.
– S. CA pegmatites, morganites would be left in the sun to “bring the pink up”
Brazilianite (green to colorless)
Bromargyrite (darkens, Ag liberated)
Calcite (colors fade)
– Elmwood, TN*
– Santa Eulalia (yellow ones from Santa Eulalia temporarily turn pinkish on 15-20 min exposure to sunlight, turn white permanently with 30-60 min exposure to sunlight.
Celestine (blue to colorless)
Chlorargyrite* (gray to violet-brown, Ag liberated)
Cinnabar (red to black metacinnabar)
– McDermitt (Cordero) Mine, NV, Pink Corderoite turns a mouse gray color
Corundum (yellow to colorless)
Creedite (purple creedites are VERY light sensitive)
Cuprite* (darkens, Cu liberated)
Diamond (yellow to green; red to pink)
– Mount Gabriel, County Cork, Ireland
Fayalite (green to blue)
Feldspar v Amazonite*
Fluorapatite (pink fades)
Fluorite (pink to colorless; green to purple; blue or purple to colorless or pink)
– Bingham, NM, blue will fade with exposure to sunlight.
– El Hamman, Morocco, Ink blue pales with 30 min direct sun exposure *
– Elmwood fluorite is reported to be stable.
– Haute-Loire, France, sky blue turns colorless with 30 min direct sunlight.
– Hilton yellow fluorite is reported to be stable.
– Navidad Mine, deep grape purple when mined, but miners put in sun for 6-9 weks to turn them pink.
– Sant Marçal, Montseny, Spain, deep blue turns dirty green with 1 hr direct sunlight exposure. *
– Weardale (Cowshill area), Pale green changed to purple almost immediately on exposure to daylight (not even direct sunlight!).
– Weardale (Rogerly, Heights, Cement Quarry, and the old White’s Level), green are all potentially unstable, though to varying degrees. Purple color appears more stable. Deep green fluorite from the Rogerly (Solstice Pocket) permanently changed almost instantly to a muddy gray-green if exposed to a LWUV lamp; this process took longer in sunlight.
Halite (blue or yellow may change)
– Huantajayite (argentian halite, contains silver halides)
– Searles lake, pink color from halophylic bacteria and algae fade with exposure to sun.
Haüyne (blue pales)
Hisingerite (red to brown)
Ianthinite (purple to greenish yellow)
Kleinite (yellow to orange)
Lepidolite (purple to gray)
Marcasite (w/ high humidity – can speed up oxidation)
Metatyuyamunite (yellow to green)
Mercury Halides like Aurivilliusite
Miersite (darkens, Ag liberated)
Mosesite (yellow to green)
Nepheline (pink to colorless)
Pabstite (pink to colorless)
Phenakite (red to pink)
– Lemon yellow phenakite from Mt Antero turned colorless after one day in sunshine.
– Orange/brown phenakite from the emerald/alexandrite deposits in the Urals turn colorless or white depending on inclusion content within hours or days if exposed to UV light.
Pyrite (w/ high humidity, light can speed up oxidation)
Quartz (most colored quartz is light sensitive)
– Brazilian amethyst
– Nebraska amethyst will bleach after a couple of days in the sun.
Quartz v Citrine
Quartz v Morion
Quartz v Rose* (fades)
Quartz v Smoky (smoky to greenish yellow to colorless)
Realgar* (red to yellow pararealgar)
– Realgar is only sensitive to green light
Rutile (pale to darker)
Scapolite (violet to colorless)
Selenite (pink fades)
Silver, native – can tarnish when exposed to light and moisture
Silver Halides (these generally darken and Ag is liberated)
Silver Sulfides/Sulfosalts like Miargyrite
Sodalite v Hackmanite* (red to green, blue, or colorless)
Spodumene v Hiddenite
Spodumene v Kunzite (pink to colorless)
Topaz* (brown to colorless or blue; blue to paler or colorless)
– Most Thomas Range, UT sherry topaz xtals turn colorless with exposure to sunlight.
– Some topaz xtals from east side of the Thomas Range, UT start out as sherry but turn pink after one to three weeks in the sun. This is due to an unusually high content of pseudobrokite inclusions. The pink is stable, at least after one year of leaving these in the sun.
– Some topaz from the Little Three Mine were collected as colorless but turned blue upon exposure to the sun. Blue crystals that came out of the 1976 and 1991 pockets became much more blue with exposure. This blue color appears stable.
– Sherry colored topaz from Villa Garcia, Zacatecas, Mexico is reported to have stable color.
– The sherry colored portions of topaz xtals from Mokrusha Mine, Urals fade and seem to turn light blue with exposure to sunlight.
– Volodarsk/Volhynsk, Ukraine topazes usually start our dark orange but fade quickly with exposure to sunlight. Bicolored samples found in some pockets (light pinkish champagne and blue) seem to be more stable (at least for 15 years).
Tourmaline (some pink, red)
– Tuperssuatsiaite specimens from Aris started out mauve but turned green.
Vanadinite (red or yellow to darker)
Vivianite (green, blue)*
– Red Cloud wulfenites will fade over time