A weather-fractured rock 


You might wonder what you're looking at here.  (Yes, it's a rock.)

The small rock sitting on the larger rock is an example of something we commonly find.  Namely, the inside of the rock is already weathered before it's even broken by someone.

I didn't take a close-up, because all I had at the moment was an old Konica C35 from a yard sale.  This was a test roll just to see if the old CdS light meter still worked (looks like it does).  I had brought this little 35mm down to the Buckwheat, one fine day this 2012.

Notice the dark portion in the right-hand half of the small rock.  It has a slightly purplish undertone to the brown, which is typical of Franklin ores when they weather.  You're looking at what many field collectors refer to as a "weather fracture".  Over the years, freeze-thaw cycles and rain cause micro-fractures to become larger, often criss-crossing the rocks with oxidized, permanently dark seams.  Gradually the big rocks crumble into smaller ones.  This happens even when the rocks are covered with earth.  In fact, this kind of weathering can happen down to at least several tens of feet in the ground.

Many mine rocks already have existing cracks due to the blasting that was used.  This accelerates the weathering process.   The relatively soft, calcite-rich rocks-- which contain most of the good fluorescent minerals-- also have the most fractures.

Cordoning rocks off from human activity doesn't really preserve them for future generations.  It simply ensures they'll weather away until those mythical "future generations" have a bunch of pebbles and silt. Of course, those generations won't be allowed to have a go at the rocks, either;   this mythical "future generation" always seems to be the infinity-th one.  That's why I'm always skeptical of extreme "cordon-it-off" environmentalism;  we're saving these things for someone in the future, but who, precisely, is that "someone"?

Allowing collectors to find and keep rocks from old mine dumps and rock piles is probably the best thing that can be done.  Once the rocks go into collections, they are protected from the ravages of weathering, at least for the duration that human beings exist.   The best conservation efforts have actually been done by those who've turned the places into collecting sites:  Buckwheat Dump, Crater of Diamonds, Sterling Hill, and so on.   

The rock cycle is constantly at work.  Good rocks are out there, but the weather is inexorably breaking them down to sand and gravel, and finally silt.   Since it seems to attack the better rocks more quickly, you might as well get out there and collect!

    

Franklin, NJ / Buckwheat Dump

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