Can the sun fade colours on rocks considerably ?

[Pleuromya]

Hi, my space left for things is becoming smaller, so I thought I'd use my windowsill. I found different things online claiming different things. Will the rock colour fade or discolour at all due to being on the windowsill? 

Many thanks. 

[Paleostoric]

Over time, the Sun and its UV rays could certainly cause some fading and discoloration of fossils/rocks, but I guess it largely depends on each specimen and the type of fossils/rocks to determine susceptibility. If they are being pounded upon by UV rays with constant direct exposure to the Sun on the windowsill, I would expect some possible discoloration, but if not, I think it should not be too much of a concern. 

[Pleuromya]

3 minutes ago, Paleostoric said:

Over time, the Sun and its UV rays could certainly cause some fading and discoloration of fossils/rocks, but I guess it largely depends on each specimen and the type of fossils/rocks to determine susceptibility. If they are being pounded upon by UV rays with constant direct exposure to the Sun on the windowsill, I would expect some possible discoloration, but if not, I think it should not be too much of a concern. 

Thanks. The exposed surfaces will be facing away from the sun, so ideally they will not encounter too much sunlight. 

[jpc]

I dug up some petrified wood a while back.  The pieces on the surface were orange,  but the pieces I actually dug up (same tree) were brown.  I left the stuff in the yard because I had no rom for 12 feet of tree in my house.  Within two weeks the brown had turned to the same orange as the other pieces.  Two weeks.   

[-Andy-]

Yes, fossils can be discolored by the sun. Sometimes, surface collectors find fossils with a different color from what is expected (e.g. a gray shark tooth instead of black). Those are called sun-bleached fossils

[Pleuromya]

23 minutes ago, jpc said:

I dug up some petrified wood a while back.  The pieces on the surface were orange,  but the pieces I actually dug up (same tree) were brown.  I left the stuff in the yard because I had no rom for 12 feet of tree in my house.  Within two weeks the brown had turned to the same orange as the other pieces.  Two weeks.   

 

21 minutes ago, -Andy- said:

Yes, fossils can be discolored by the sun. Sometimes, surface collectors find fossils with a different color from what is expected (e.g. a gray shark tooth instead of black). Those are called sun-bleached fossils

Thanks. I'll be sure to keep an eye on these rocks, as the bands of colours are very interesting. 

[Mark Kmiecik]

10 hours ago, jpc said:

I dug up some petrified wood a while back.  The pieces on the surface were orange,  but the pieces I actually dug up (same tree) were brown.  I left the stuff in the yard because I had no rom for 12 feet of tree in my house.  Within two weeks the brown had turned to the same orange as the other pieces.  Two weeks.   

May have been due to exposure to the atmosphere, or even to the termination of exposure to minerals in the soil. I would guess that lack of exposure to direct sunlight would dramatically extend the timeframe, even to beyond a lifetime depending on the minerals exposed.

[FossilNerd]

I’m not sure if the sun and it’s UV rays will damage and discolor fossils, but my job requires working in the sun all day; after a month or so my shirts are very faded (especially the back) and I have seen more than one thing discolored and sun faded while sitting in a store front window in short order (a week, maybe two?). Just from my personal experiences I would be concerned about putting my fossils in the window sill.

 

That being said, there are UV blocking plastic films that can be purchased online or from home improvement stores that go over your window. You can find them with tint or without. I would recommend using some of this if the window sill must be used.

[siteseer]

6 hours ago, FossilNerd said:

I’m not sure if the sun and it’s UV rays will damage and discolor fossils, but my job requires working in the sun all day; after a month or so my shirts are very faded (especially the back) and I have seen more than one thing discolored and sun faded while sitting in a store front window in short order (a week, maybe two?). Just from my personal experiences I would be concerned about putting my fossils in the window sill.

 

That being said, there are UV blocking plastic films that can be purchased online or from home improvement stores that go over your window. You can find them with tint or without. I would recommend using some of this if the window sill must be used.

 

The sun can definitely bleach out, dull, or darken a fossil,  Sometimes, you count on it.  I found a fossil leaf around Goshen, Oregon and my friend said to leave it in the sun at home.  For some reason the fossil becomes more distinct from the matrix, darkening while the matrix stays about the same color. 

 

The most startling color change I've ever seen in a fossil was in a friend's quarry in Bakersfield, CA.  I dug out a watermelon-red Carcharodon hastalis tooth, and right before my eyes within seconds, it dulled to more of a dark blend of color.

 

Thanks for the idea about the UV-blocking plastic film.  That would also help anyone displaying photos or posters in a sunlit room.

 

Jess

[LabRatKing]

Heat and UV exposure will cause color changes. Both act as the extra engy need to cause redox reactions (think rust) where oxygen combines with the minerals and metals in the fossil. Weather exposure causes "bleaching' just as it does with wood and cloth. This is why geologists always shoot for a "fresh face" on samples as exposure to the elements will in time change the appearance of rock.

[Mediospirifer]

Then there are a few rocks that change color in sunlight, and fade again when stored in the dark! This is the same reaction as seen in self-adjusting sunglasses (reversible photochroism). It's pretty cool to see.

 

I have a piece of Hackmanite that was a pale cream color when I bought it, that turned purple in patches under my UV lights over the course of a couple of days in my fluorescent light box. The purple areas fluoresced orange, and are quite phosphorescent. It does fade again when I keep it in the dark, but that takes a few months. I'll have to take some pictures of it sometime showing the extent of the color change.

 

Geology is full of surprises! 

 

[LabRatKing]

4 minutes ago, Mediospirifer said:

Then there are a few rocks that change color in sunlight, and fade again when stored in the dark! This is the same reaction as seen in self-adjusting sunglasses (reversible photochroism). It's pretty cool to see.

 

I have a piece of Hackmanite that was a pale cream color when I bought it, that turned purple in patches under my UV lights over the course of a couple of days in my fluorescent light box. The purple areas fluoresced orange, and are quite phosphorescent. It does fade again when I keep it in the dark, but that takes a few months. I'll have to take some pictures of it sometime showing the extent of the color change.

 

Geology is full of surprises! 

 

Utah topaz is notorious for going from smokey orange brown to crystal clear after just a few days of UV exposure. If you like, we can have a UV reactive mineral/rock show in the geology forum on here, I have access to both short and long wave in addition to broad spec...and 40 or so specimens!

[Mediospirifer]

20 hours ago, LabRatKing said:

Utah topaz is notorious for going from smokey orange brown to crystal clear after just a few days of UV exposure. If you like, we can have a UV reactive mineral/rock show in the geology forum on here, I have access to both short and long wave in addition to broad spec...and 40 or so specimens!

 

That sounds like fun!

 

I also have both long and short wave UV lights and lots of specimens (including some fluorescent fossils ). I'll just have to work on a photography setup that does them justice!