HOW-G-02 Origin: Zimbabwe Grade: A Dimensions: Approximately 30-40mm Weight: Approximately 20-30g Origin: Zimbabwe Grade: A = good Howlite pebble approximately 30-40mm Patterns and colors may vary from one stone to another. Howlite is a stone belonging to the calcite group. It is composed of silicon, calcium silicate, and a significant amount of boron. More precisely, it is a hydroxylated calcium borosilicate. Its crystallization system is rhombohedral, meaning it resembles a kind of cube with faces that are not square but diamond-shaped. This stone is partly recognized by its white, opaque, and porous appearance.