This cathedral amethyst crystal is 55 lbs and measures 19.5" high x 9" wide by 7" depth. Note that crystals are not evently shaped. We measure at the larger points for all three dimensions. The back of this amethyst (see the third photo) is protected with a special compound to prevent crumbling - this is a typical process that is done to protect the integrity of the crystal.
 
Cathedral stones are large, upright, mostly free-standing crystals. Amethyst is produced by the presence of trace amounts of iron and manganese in a clear quartz, giving it it beautiful purple.