Feature●1/2 lb rough common Green Opal for rock tumbling●Pieces range in size from 15 to 30 grams, in length (average) from 1" to 1 1/2". Occasionally a piece may be a bit smaller or larger than these average numbers.●Stones in the photo are wet. Your stones will not be as bright until they have gone through all of the required tumbling and polishing steps.Description Nicely sized stones for rock tumbling. Mohs hardness ranges from 5 to 6.5. Stones are mined in Madagascar. 1/2 lb will have anywhere from 5 to 8 pieces per bag.