The classic colour for hydrogrossular garnets is light green. White and brown are two other common colours for the hydrogrossular garnets found on Gemstone Beach in Southland. This stone is a good example of the brown variety:
The shore of Te Waewae Bay is the only location I know for hydrogrossular garnets in the lower part of the South Island – they can also be found in the Nelson area. The white ones shine brightly on the beach, vying with white quartz to be the most conspicuous. Green ones are much harder to spot – often I have to be right on top of one to recognise it. The brown ones are somewhere in-between for elusiveness.
Hydrogrossular garnet stones have a slightly waxy feel and are often shiny and smooth when found. They do not need to be polished for you to appreciate them. Some people I know wear a pendant of an unpolished stone. However, polishing increases the smoothness and shine. Stone #20 was tumbled with a batch of diverse Gemstone Beach stones – first in 400 grit then 600 grit (I normally skip the 600 stage for hydrogrossular garnets). It spent 17 days in tumble polish followed by 9 days in borax. This length of time for these last two stages are not necessary for hydrogrossular garnets, although it does not hurt them. Stone #20 is 4 cms long, 3 cms wide and just over 1 cm deep.
It is thought that hydrogrossular garnets have washed down the Waiau River (or some ancient version of such a river) from the mountains of Eastern Fiordland. Large hydrogrossular garnets were used as hammerstones by local Maori. The sea seems to keep turning up the smaller stones on the beach between the Gemstone Beach carpark and the mouth of the Waimeamea River. These are the stones that are most sought on Gemstone Beach. Every now and then I come across a fossicker who seems to be almost exclusively looking for them.
In June 2021, I was privileged to be gifted two beautiful specimens of hydrogrossular garnets by Michelle Grace who has spent a lot of time at Gemstone Beach in the past. The light green one on the left (below) is very heavy. The middle one, dark in colour, has a hue unlike any other hydrogrossular stone I have seen. The large brown one on the right (below) is another fine specimen in Michelle’s collection.
Michelle had seen my Posts in the Facebook Group “New Zealand Lapidary, Rocks, Minerals, Fossils” and invited me to visit and see her stone collection in Riverton. She unpacked it for me and laid the stones out for a privileged private viewing:
The Index to the January 2022 Stone of the Day Series is here.
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