Porphyry, any igneous rock consisting of large crystals in a mass of much smaller crystals. The large and small crystals usually are of different minerals; the rock is generally named according to its major component (for example: granite porphyry). When cut and polished, porphyry has a beautiful pattern and contrast of colors. It is used for tombstones and ornamental panels.
Albert Einstein was a pretty smart guy. When you look up the word "genius" in the dictionary, so the saying goes, it's a pretty safe bet you'll see Einstein's mug. Think you’re smart enough to take on a quiz about the famed thinker?
While routinely scanning the stars, NASA scientists came across something they didn't expect to see: a vast area of space empty of stars, planets and matter.