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Registered Member #56
Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445
I am kind of a rock collector (if I see a cool looking rock I take a few home with me), and I was wondering about a few in particular...
Mainly I was wondering about these ones I found while in the mojave desert... There had recently been a pretty powerful earthquake (forgot how much but higher than a 6) with the epicenter right near where were camping. We had been to the area several times before, and noticed a few, but after the quake there were quite a few more. We even found one that had been sheared in half with the two pieces about 10m apart
In any case, there were these really cool (as if just to prove my nerdship) rocks, that were definantly created in some type of volcanic flow (the area is a few miles from a large deposit of volcanic rocks). They looked almost like someone had poured wax on the rocks, a really flowing smooth surface on top and sharp/sandy desert rocks on the bottom. Most were 1-3" on a side and 1-2" thick.
But here is where things get interisting... They glow green when exposed to uv light
Of all of 16 years of rock collecting I have found 2 other rocks that glowed (both in the same spot), they were petrified wood that glowed red. Finding that these glowed was quite a suprise (especially since the rock that comes to mind with green florscense is uranuin...anyone with a geiger counter want one?)
here are some pics of ones in normal light...
Hre is the first one under a uv light. I couldn't get any others to show up at all, but they all glow a prety strong green. On some of them not all of the translucent rock is green, on others it is. That one is mostly green. There are some little clear crystals in the center of the first one (just visible in the first pic)
So it is clear that the green part is an impurity in the translucent rock...
Any ideas as to what it might be or any other random comments?
Dunce. Registered Member #28
Joined: Fri Feb 03 2006, 03:29AM
Location:
Posts: 76
Oh no, you have Uranium-235! You've probably already got a lethal exposure.
Try testing the radioactivity with a neon bulb geiger counter, you turn the voltage up on a neon just before it strikes, then bring the rock near the bulb, if it strikes, that would imply that the radiation is ionizing the gas.
Registered Member #56
Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445
Aww, so I didn't find a uranium deposite right next to my dad's friend's dad's mining claim (they don't do any mining on it, but there are a lot of mines in the area; not sure what they are after, but I see a lot of green tinted rock (copper?) and I hear they were after semiprecious minerals.
Hmm, suppose it cold be that... I tried to get find a piece with crystals developed enough to tell the structure, but there weren't any. I saw a few planes that met at right angles, but also some that looked like they would have 6 or 8 sides...
To jim, wouldn't the glass block out all of the radation? I tried a while ago to make on go with a Pb-210 needle (.1uCi on the tip of a needle) ) and didn't have any luck...
Registered Member #268
Joined: Tue Feb 28 2006, 02:44AM
Location: Ontario, Canada
Posts: 48
According to a geologist teaching at Queens University in Kingston, ON:
wrote ... Many rocks glow green, blue, yellow and red under various UV lights. I say lights because the wavelength of UV is anything shorter than violet (400nm) therefore even the light-emitting diodes at 370nm can cause fluorescence.
You should check out the website of the fluorescent mineral society... they've got a forum as well on yahoo.
Minerals like emeralds, corundum (rubies), kyanite, apatite, vernerite, willemite.... are just a few examples of minerals that can be identified using their fluorescence spectra. Not all specimen of these minerals will fluoresce, they require a certain amount of an "exciting element" in their crystal structure to do so. For minerals like Kyanite and corundum the element is Cr. For scapolite it is S (sulphur), and for calcite it can be Europium (Eu), Uranium or others.
World-known location for fluorescent minerals: Mount St Hilaire in Quebec near Montreal. The Franklin Hills in New Jersey, and also another location in Greenland (sorry don't know how to spell or pronounce that one)
Hope this helps.
Cheers! Luc
Looks interesting. I know you are in California, but maybe this is useful anyway! is the site he mentions for the Fluorescent Mineral Society.
Registered Member #195
Joined: Fri Feb 17 2006, 08:27PM
Location: Berkeley, ca.
Posts: 1111
I have seen thease kind of rocks in musiems and definatly each minral floresses in differant colors and has differant cemical make ups. This is kind of out of this thread but there are types of fungusses that are phospheresant and glow in the dark.
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