Some More Recently Polished Stones from Slope Point and Kakanui

Here are 14 tumble polished stones, seven from Slope Point and seven from Kakanui, many of them just recently tumbled. About two weeks ago, I finished tumble polishing a 6lb barrel of Slope Point stones, half of which had been given to me by fellow fossicker Oliver Simpson. Slope Point is the southernmost part of the South Island, about 70 kilometres east of Invercargill. There are three or four beaches there that are productive for fossicking, though they are difficult to access due to some steep slopes and the need to walk a way to reach them. See here for an account of a fossick at one Slope Point beach, and here for an account of another. Many of the Slope Point stones have arisen from Jurassic Era volcanic activity and debris flows. Most of the following seven Slope Point stones come from my recently tumbled batch. The most interesting ones would originate from Oliver, for example, the petrified tree fern stone (photos below). In her booklet, “Gemstones” Jocelyn Thornton writes on the pebbles to be found at Slope Point (page 35): “The prize is petrified punga, found as black nodules barely showing the eyed grain of the fern.” You have to hold the stone at an angle to the light for the lines in it to become visible.

Another I am sure to have come from Oliver is a chrysanthemum rhyolite, a form of spherulitic rhyolite, a volcanic rock. On Mindat.org, it is noted: “The chrysanthemums are cross-sections through large spherulites that formed in the rhyolite” (spherulites are small spheres with a radiating structure).

The following stone is also a rhyolite. Jocelyn Thornton writes in “Gemstones”: “‘Flower garden’ is the local name for rhyolites with white and grey circles and centres”.

The next two stones are flow-banded rhyolites:

The sixth Slope Point stone is probably a volcanic breccia, a stone consisting of the melding together of small fragments from different sources:

The seventh and last Slope Point stone is a spherical shaped petrified wood one. Typical of much Slope Point petrified wood, it is very dark, with just some brown wood-like shapes on one side.

The next seven stones are from Kakanui’s Seadown Beach. See here for an introduction to Seadown Beach, which starts just two kilometres north of Kakanui village. There are interesting jaspers to be found on this beach, including hematite jaspers like the small one below. The silvery grey hematite in the stone is a type of iron oxide.

Various types of quartzite can be found at Kakanui too, many with tiny quartz crystals in them. The origins of quartzite are mentioned in the Wednesday 26 May 2021 entry in this Post.  The first quartzite below is a small colourful yellow one with some red streaks, the second a very dark brown circular stone.

The largest of the 14 stones could also be quartzite – it is full of clear quartz crystals.

The next two stones look like a kind of quartz with light-coloured mineral patterns in them.

The final Kakanui stone is a fossilised sea floor one, containing many tiny fossils. See this Post for more information on this type of stone. After tumbling in fine grit, such stones feel soft and waxy, and there is no need to go on to tumble them in polish.