$USGT Typical ranges of chiastolite within the Blue Wing Mountains begin with smaller crystals occuring toward the southern and western zones of the andalusite-bearing hornfels. Larger crystals, to 3 cm in diameter, occur in the central portion (particularly at 40o 20.319’N, 118o 57.502’W). Many chiastolite crystals exhibit partial to total alteration to sericite. When polished, the sericitic alteration imparts a slight iridescence to the crystal cross-section, lending a moonstone-like quality. These cream-colored crystals are translucent and visually appealing.