[Rockhounds] Parabolic rock cutter & psilomeline

[Rock Currier]

I personally think using a parabolic shaped mirror to cut rock would not be 
possible. If you had a big enough dish, the focused beam might be able to 
disrupt the structure of a thin slab, but to cut blocks in a quarry I think 
would be impossible. You might be able to cook the surface of the rock a 
little, but as the cut proceeded beyond the surface the focus of the dish 
would be blocked by the adjacent rock and you would loose any possible 
"cutting" power from the focused suns energy.



Psilomelane is of course not a mineral, but rather a name for various 
massive manganese oxides. Looking at the picture makes me think it is a 
piece of the old classical Mexican cutting material that used to be around a 
lot in the 50s and 60. It was commonly called black malachite by the old 
cutters and was a total misery to cut because it would gum up diamond blades 
and turn everything black. I got a double fist size piece when I bought out 
an old estate a couple of years ago and had it shaped a little and contour 
polished as a piece for my collection. The guy who did it for me, bitched 
and moaned about what a mess it made. It has to be the same stuff.



Rock