Trinitite

We are asked from time to time where one can get Trinitite, the glassy mineral caused by the test of the "Gadget" atomic device at Trinity Site on the White Sands Missile Range. For several years after the test, the material was poached from the site by the truckload. It was never officially distributed, and there is no guarantee that any glass called Trinitite is authentic without very exacting analysis well beyond this writer's understanding.
That said, we have been told that there is enough out there in circulation that it is unlikely that anyone would go to the trouble to try to make counterfeit Trinitite. As to where to buy it, we will leave that up to the resourcefulness of our readers.

Comparing Hardness of Rocks

We were asked how students can compare the hardness of different rocks, especially scoria and volcanic tuff.

To compare two different materials’ hardnesses, one approach is to try to scratch one with the other. We suspect, although we haven’t tried, that you will find the scoria scratches the tuff and not vice versa. This method is used by gemologists, who know that a rock that can be scratched by a common steel nail will be too soft to take a high polish. Steel is just about the perfect hardness to make this determination. Agate is harder than steel and polishes to a high luster, limestone is softer and remains dull no matter how long it is polished. A diamond should be able to scratch almost anything, and talc shouldn't scratch anything.

Ultimate Source Of Nuclear Energy

We have been asked during our energy program how nuclear energy fits into the mix when all of our other forms of energy derive ultimately from the sun.

The tie-in is actually pretty interesting. Most of the energy we use comes directly or indirectly from the sun, which is “burning” hydrogen created during the Big bang. Stars fuse hydrogen atoms into heavier elements only up to iron. The planets, and all the elements heavier than iron (further down the periodic table) are composed of stuff created in supernovae, dying exploding stars, that preceded the sun. Only a supernova is energetic enough to create the exotic and unstable elements up to uranium. So nuclear reactors, which run primarily on uranium, ultimately derive their energy also from stars, although not our sun.

Cross Puzzle with 4 pieces

You asked if the puzzle in TechLab with four pieces actually reassembles into one large square.

 Two small squares are easy.

The hint posted alongside this puzzle is that the square has twice the area of the cross. The only way this can be, using the same four pieces, is if the square has a hole in it with the same area as the cross. We will be the first to admit this is a sneaky solution.

In this case, the hole is actually the same shape as the cross. The drawing shows the cross pattern with one piece rotated into position as a corner of the square pattern.