Here are four Kakanui stones that have been tumbled only in 400 grit. I have discovered that tumbling them further does not improve them. As it is, they come out of the 400 tumble smooth and waxy-feeling, and showing clearly the often-tiny fossils within them. I have previously referred to them as fossilised sea floor – they are a kind of limestone (I now – 2025 – refer to them as fossiliferous limestone).
When found on the beach, these stones are often unremarkable, being whitish, sometimes showing some darker grains within them, sometimes hinting at the small fossils in them, often feeling grainy and powdery. Some of them have holes in them, some of them have no fossils. But many of them turn out to be very intriguing. About 900 metres down the beach from where I park my car (at the end of Seadown Road), there are usually some rocks poking through the sand that are made of the same stuff, though I have not seen the tiny fossils in them that these stones contain.
I tumbled a batch of these stones in 400 grit in a 3lb barrel recently. I did not open the barrel until after 11 days of tumbling. Inside was a thick fine-grained slurry and I worried initially that the stones might have been worn down too small. It turned out they were still of a good size – I have usually tumbled them only for about 7 days, and in future will restrict them to 6 to 7 days in the barrel. These four stones were among the most interesting in that batch – the tumbling revealed much more than was able to been seen in the “rough” stones. Here are the first two stones:
Here are Stones 3 and 4 – Stone 4 is less grainy and maybe more dense than the other three:
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