Fossils And Exposure To Uv Rays

[Sirrah]

Wondering if fossils could be damaged by prolonged sun exposure. Should collections be placed away from the sun rays?

[Wrangellian]

I'm not sure but I would keep them out of the sun just in case. I think it's usually the color that might be affected, if anything, but maybe also repeated heating and cooling could be detrimental. Let's see what others have to say..

[Trevor]

I agree, it changes color then the heat loosens the fossil and the cold hardens it and this can create damage. Thats why desert teeth are whitish and kind of broken.

Edited October 27, 2012 by Survivor

[Auspex]

UV radiation is energetic, and destructive. The first rule of any conservator is to limit, as far as is practicable, the exposure his collection receives.

[Al Dente]

Several years ago I took a trip to the Peace River and found an assortment of bone. All were dark brownish black. I put a horse metatarsal and a piece of tortoise bone on a shelf that is exposed to direct sunlight during part of the year because I had no where else to store these large bones. They slowly lightened in color while the smaller bones stored in cabinets stayed dark. Here is a picture of what they now look like:

Large teeth found at the Lee Creek Mine usually have lighter parts where they were exposed to the elements. Here's a Carcharocles tooth with a light patch on the root. This part of the root was all that was exposed when I found it.

[erose]

Bleached by the sun. Seems to apply to fossil bone as well. I believe much of the damage is done by the shorter UV rays. Not 100% positive but I think it would take direct rays of sun for short waves to have an effect.

[Sirrah]

this is all very helpful, thanks! Gotta find a place to display them out of the direct sun then.

[pleecan]

If organic molecules are present in the specimens... UV will destroy them... the infra-red component of sun light will cause thermal stressing.... weaken structures via micro cracking.... some museums will even ban flashes from cameras to protect their sensitive artefacts on display. ... so keep specimens out of sunlight is a good idea... ( unless one is photographing them...)

Edited October 27, 2012 by pleecan

[painshill]

This advice comes from the American Museum of Natural History:

“Most fossil specimens are not directly affected by either visible or ultraviolet light, but other mineral components of a collection can change color, change phase, or decompose in response to high light levels. A bigger concern for paleontology collections is the ability of light to affect adhesives used in the preparation or preservation of a specimen, as well as its effect on other collection housing materials. Light damage is cumulative and irreversible. As a result it’s a good idea to limit light exposure if possible.”

Adhesives in the Cellulose Nitrate class (such as Duco Cement, Randolph's and Glyptal) have a tendency to yellow with age and exposure to UV light – as well as suffering severe shrinkage which may damage specimens through stress.

Edited October 29, 2012 by painshill

[jpc]

Years ago I collected a fossil log about 12 feet long. Only the first foot had been exposed on the surface and was an orangy color. The other 11 feet that I dug up were dark brown. I put the log in my yard and within two weeks, the UV had turned the log to the same orange as the initial piece. It can happen very quickly.