I am giving some tumbled Ward Beach stones to Ronnie and Ian who run the Flaxbourne Motels in Ward, Marlborough. This Series features a selection of these stones. Part 1 dealt with trace fossil limestone pebbles, Part 2 with other kinds of limestone pebbles, and Part 3 with veined stones as well as stones with dendrites. This Part presents Ward Beach stones that contain a mix of soft and hard material. These are difficult for a tumble polisher as the soft material wears away much quicker in the tumble barrel than does the hard material. So such stones have to be treated with some care. Part 5, the last in the Series, looks at hard stones.
In a Post reporting on my most recent fossicking visit to Ward Beach in March this year, I noted how the rocks to the south of the carpark appear to be limestone with darker flint patches and nodules. Flint is often to be found in association with limestone. Flint is a sedimentary cryptocrystalline form of quartz. In other words, the quartz has been put under pressure and heat to the extent that the crystals become too small to be recognised and separately distinguished even under an ordinary microscope. The following are stones that appear to have hard (flint) and soft (limestone) material in them, the hard material being more resistant to erosion.
The next set of stones also appears to be a mix of soft and hard material but in a more complex way and not always a mix of limestone and flint:
The final Post in this Series features Ward Beach stones that are hard in nature, the usual kind for tumble polishing.
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