In this stone, found on a Slope Point beach in 2021, many small fragments are packed tightly together. [Though see the Note at the end on this Post about whether it is breccia or not.]
Stone #25 was tumbled in 400 grit then in 600 grit. After 13 days in tin oxide tumble polish, it had a three day borax burnishing period, being in the same 3lb barrel as Stone #10, Stone #12 and Stone #16. There are some remaining tiny areas that are not completely smooth but I proceeded with the polish as I did not want to reduce the stone further. It ended up being 4 cms long, 2 cms at its widest, and 1 cm thick.
[NOTE, 25 January: My limited knowledge of geology led me to think this could be breccia. However, the “fragments” are unusual and I had at the back of my mind the thought that they could be crystals of some kind. After I posted the Post, Mathew Vanner kindly made the following comment on the Facebook Group “New Zealand Lapidary, Rocks, Minerals, Fossils“: “I am not sure that this rock is brecciated – I think it is an igneous with large maybe feldspars in a fine groundmass.” Mathew has a background in geology and the Southland region (see the Post on Stone #17) and his suggestion is probably more reliable than my original thinking.]
The Index to the January 2022 Stone of the Day Series is here.
2 thoughts on “January 2022, Stone of the Day #25 – Slope Point Volcanic Breccia?”