HQ Andamooka Black Matrix Opal Irregular Pebble Bead StrandAndamooka Black Matrix Opal is a unique and striking variety of opal found in Andamooka, South Australia. Physically, it is characterized by a porous host rock (matrix) that contains precious opal scattered throughout, creating a speckled or "galaxy like" effect. Naturally light in color, the matrix is often treatedwith sugar and acid or smoketo darken the background and enhance the vivid flashes of green, blue, red, and orange that the opal produces.