This is the fifth in this Series reproducing my recent regular Posts in the Facebook Group “New Zealand Lapidary, Rocks, Minerals, Fossils”. The first Post in this Series is here.
Saturday 15 May 2021: The failure to polish… There are two processes I enjoy – finding interesting stones, and seeing them tumble-polished. The first does not always lead to the second – sometimes a stone does not polish, or not very well. After a few years’ experience, I have a good idea which stones will polish and which will not. Then there are those stones that look really interesting but I kinda guess they may not polish. Some I try anyway – because the stone is so interesting, and I have hope. I found this stone on Birdlings Flat on 24 August 2020 and finishing polishing it two days ago. It is 3.5 cms long.
It didn’t really polish, but remains fascinating and will be kept in my collection. It is volcanic, [probably andesite], would originally have had lots of holes in it, and these holes have filled with minerals as water moved through over thousands and thousands of years. Generally, the infill material polished much better than the host material.
[Comments on this Post included “Some of the infill is banded and is tiny agates… Pretty red matrix too”, “Likely originated from the Rangitata River” and “See these in the Hinds River too. Varying sizes”.]
Sunday 16 May 2021: Birdlings Flat quartzite, recently tumble-polished, 5.5 cms long, still 3 or 4 very small areas of shallow rough places on it but I didn’t want to reduce it in size any more. It is far to interesting to me in its complexity to risk losing some of that by further tumbling.
Monday 17 May 2021: Banded beach agate, Birdlings Flat, just finished tumble-polishing. Five cms long, polished to a very smooth finish. I was amazed that the small marks caused by bashing against other stones and rocks in the waves actually seem to go quite deep, were not removed by tumbling (400 grit then polish).
The next Post in this Series is here.
3 thoughts on “FB Group Posts: 15, 16 & 17 May 2021 – Birdlings Flat “Polish Failure”, Another Birdlings Flat Quartzite, and Birdlings Flat Banded Agate”