These quartz pebbles frequently turn up all over southern Scotland. Washed down from the high regions where they form, these pieces of quartz crystals have been naturally rounded through weathering. 
These Scottish crystals are washed into the rivers gradually, where we scoop them up. They range in colour from milky quartz to slightly translucent smoky quartz, with red or green patches in them. 
We are tumbling these in the Evans dual with a rubber barrel from a Nat Geo hobby tumbler. You will soon be able to buy these rock tumblers on Amazon through our website. Keep in mind that rock tumblers on TSC are for UK sockets and wattages and are unlikely to work elsewhere.
We have two of these Scottish quartz with iron oxides and/or chlorite schist for sale at the moment but we will add more.