A nodule that was cut in half and polished to exhibit beautiful blue Turquoise in different patterns. Most Turquoise is blue-green. This Turquoise from Kazakhstan has a true blue color, with lighter and darker hues
Boulder Opal is precious opal, which occurs in deposits within weathered sedimentary rocks of the Cretaceous age. It forms as a result of silica-solution seeping into spaces in an iron rich type of sandstone, called ironstone, & then solidifies. These spaces could be large & flat, which lead to flat, clean-faced opals (boulder-opal); or the spaces could be very small & scattered in an attractive pattern throughout an ironstone nodule which leads to o typical Koroit or Yowah-nut type opals.