First the article by Cecil and a relevant topic on the boards discussing it.
It seems that the agreement is while Superman may be able to squeeze a lump of coal into something, he wouldn’t easily produce a faceted diamond like the kind you’d wear on a ring. Impurities in the coal, not to mention the shape of Superman’s hand and the uneven pressure, and possibly the lack of heat, would contribute to a very hard but decidedly non-diamond rock.
My question is a little different. What would you get if you could squeeze a coal or some other rock into something very small? I’m thinking that if one takes a rock the size of a fist, then puts it into some kind of compression chamber that is sealed, and crush that thing into the size of a pebble, what would you get? Just a smaller, denser, harder version of that rock?
The discussion mentions possibly that the coal in Superman’s hand would turn into a goo, or dust, and it would leak out, but suppose it was completely sealed. They also mention heat, but I’m assuming that such friction would create some heat by itself, though maybe not 3100F of heat.
The result, at the very least, should be a fused piece of rock that’s smaller but denser, right? Or would it fall apart lacking the amount of heat it would take to fuse together? And what different results would you get using, say, a pile of sand vs. a regular rock of some type like sandstone?
If you compress it that much (which would take truly horrendous amounts of pressure), then what you’re left with won’t be describable as “rock” any more, and it’ll expand back to near its original size as soon as the pressure is released (explosively, if the pressure is released quickly).
There are quite a few examples rather easier than diamond (which isn’t actually a metamorphic rock). Consider limestone or chalk. Both calcium carbonate. If you apply heat and pressure you get marble.
So it is possible to change one type of rock to another simply be crushing it with great force?
As for expansion, why would it expand? Supposing that a diamond is harder and denser than everyday rock, the diamond doesn’t expand and turn into a different type of rock, why would a crushed rock not retain its shape and size?
A diamond is of course an amorphous lump. It gets pretty facets and a symmetrical shape by being carefully cut along the shear plans of the crystal. Of course, if superman squashed a lump of coal into what looked like a melted lump of cloudy glass, it wouldn’t look quite as cool in the comic books.
Diamonds tend to include miscellaneous flaws and inclusions as a result of impurities in the original material. The size and number indicate the quality of a diamond - the most expensive have the least inclusions for the size. Diamonds also pick up colours (blue to brown) from minor chemical impurities.
The important thing about liquids and solids is that (in general) they are virtually incompressible. a lump of coal is not a marshmallow. If you try to squeeze it even a little smaller than original size, that will take enormous pressure. Compression creates heat. When you let go, its not going to rebound to double its squashed size, and if the molecular bonds have re-arranged, there’s no guarantee they retain that arrangement, and no guarantee they return to earlier configuration - I guess it depends on the stability of the new molecular arrangement. Crystals generally tend to be the least chaotic and therefore the more compact arrangement of the atoms.
With uncommon exception (and diamond is actually one of them, as is the other most common mineral, silica) the atoms in solids are generally close-packed. Hence by attempting to compress them you are attempting to compress the atoms themselves. That can be done. But you are squeezing electrons into the same physical space, which means, courtesy of the Pauli principle, that some of them have to go to empty (much higher energy) states. This is where the force you supply does its (tremendous) amount of work.
But assuming you have arbitrary amounts of force available, if you squeeze a rock to something that is 1/10 its size, say, what you will get is a close-packed (i.e. hcp or ccp) array of atoms that are generally about 1/10 the size of normal atoms. How much the properties change is hard to know. Obviously the density does. The optical and electronic properties – what it looks like, how it conducts – may change, depending on how the reducing in density affects the band structure. I would vaguely guess as a general rule you get increasing metallic character, just on the grounds that you’re making it so much easier for electrons to delocalize, so you can look for a material that is more metallic in appearance and behaviour.
The pressure would be phenomenal, of course, and if you release the pressure, the stuff will revert back to its normal density state, with a really impressive release of energy.
If you really really squeeze, reducing the size by a factor of a 10 million or so, then you will enter the regime of nuclear re-arrangements, and your material will turn to neutronium. I don’t think small amounts of neutronium are stable, but I have no idea how it reverts to normal matter. Probably some drastic nuclear reactions, e.g. a horrible flood of betas and gammas accompanied by fusion as soon as there are enough protons.
There is a whole field called “experimental petrology” which consists of using some very expensive lab equipment to simulate the pressure and temperature conditions at various points inside the earth. I’m not sure what the current cutting edge of that field is, but I think they’ve managed to simulate pretty much all the conditions in which solid rocks exist in the earth (including into the mantle) and have moved onto exotic rocks and quasai-minerals that form in conditions that don’t exist in nature.
The difference in density between diamond and coal is due to the difference in which atoms there are and how they are arranged. Coal is mostly a mixture of carbon and hydrogen in various complex, loosely-packed molecules. A diamond is (nearly) pure carbon, with the atoms arranged in an atomic lattice that’s just about the densest packing you can get of carbon under normal conditions. It doesn’t expand back into coal because that arrangement of carbon atoms is very stable once in that form.
First, you’d get fusion into larger atoms (well, depending on how hard you squeeze and the actual atoms you started with.) Later you’d get nutronium, the contents of a neutron star. Keep squeezing and you’d get a very tiny black hole, which would disappear almost instantly due to radiation.
At least, that’s my “science-fiction-educated” version. I’ll step aside while someone who actually knows what they’re talking about answers.
