Like all of Mark's UV marbles, this one is made out of 100% uranium glass, and thus it lights up like a Christmas tree on fire when you put a black light on it. Seriously, it is unbelievably bright! Usually when I take the black light pics, I have to set the exposure to either 4 or 8 seconds in order to get enough ultraviolet light in there to light up the UV glass for a good shot. But with Mark's marbles, even ONE second is too much, as you can see in the 2nd picture. Truly amazing glass!!

This marble is from Mark's geometric air trap series, and has a pair of rectangular air traps inside of it. What's amazing is that the two air traps are on different planes within the marble, two different geometric levels of existence! A true wonder in marbledom, seriously cool. Awesome collector piece here, large and in charge!! Signed 'Matthews 2001'.