Quartz, rock crystal considering the clarity, is a pretty good bet. The iron stains are just in the fractures. When smooth like that can feel waxy however~~
You may not want to do it but try chipping a bit of it and see if it flakes like glass. Reason being is your description of it feeling waxy and the rectangular fracturing indicate to me it could be a massive piece of calcite as well. Massive calcite does not necessarily have to have planar cleveages like smaller crystals and when chipped will produce grainy flakes instead of glass like chips. Calcite will chip fairly easily~ quartz wont. Use a sharpened point.