February-March 2022 Fossicking Trip: Stone of the Day #19, Big Gemstone Beach Hydrogrossular Garnet

When I arrived at the beach today for my second-last fossick here this trip, the wind was blowing, and it felt cold. So I put on a woolen hat and scarf and a windproof showerproof coat. Being comfortable and warm, I ended up spending four and a half hours on the beach, walking from the Gemstone Beach carpark at high tide to a few hundred metres past the Waimeamea River mouth. At 4 pm, I was on my way back, approaching the river mouth, when I found the Stone of the Day, the biggest hydrogrossular garnet I have found on Gemstone Beach.

Stone of the Day #19.

The stone was sitting on coarse sand, at the waves’ edge. It is 6.5 cms long, 4 cms wide and 1.5cms thick, fitting perfectly, and solidly, into my palm.

Other side of Stone #19.

It contains the four common hydrogrossular garnet colours – green, white and brown with a hint of yellow. It has the typical waxy feel. I found three further hydrogrossular garnets soon after, any of which would have been enough for me on its own. One was a very light gray, one was a very light green with a spot of rust, the third was brown.

Three hydrogrossular garnets found shortly after I found Stone #19.

The three stones with Stone #19 (top).

I had earlier found another hydrogrossular garnet, mainly cream in colour:

Gemstone Beach hydrogrossular garnet.

When holding a torch behind the hydrogrossulars, the creamy yellow and brown ones are opaque, not letting light through, while Stone #19 is partly translucent (see below left) and the light gray stone is practically fully translucent (see below right).

Stone #19.

The very light gray hydrogrossular garnet.

The material/mineral that provides colour to the stones appears to add the opaqueness.

An hour before finding Stone #19, I found a real mystery stone, a mystery to me at least. It has a lot of small furrows in it but appears to consist of a relatively clear and translucent glassy material which is smooth between the furrows. [It was later suggested to me that this was also hydrogrossular garnet, and tumbling in 400 grit, which removes a very thin outer layer, seems to bear this ID out.]

Mystery glassy stone.

Torch held behind stone.

Among the other stones I collected today:

When I initially arrived at the carpark at 12.45 pm, four camper vans were just leaving. On the beach, there was only one other fossicker. During my walk down the beach, I noticed only a couple of people appeared behind me. When I returned four and a half hours later, only a handful of people were on the beach in front of the carpark. The cool afternoon, on a weekday, likely discouraged others.

Upon arrival, one fossicker on the beach.

At the end of my fossick, a handful of people on the beach in front of the carpark.

Other beach scenes from today:

Driftwood at the back of the beach, against the cliff.

Banks of stones on Gemstone Beach, more than a kilometre from the carpark. The top of the stone bank would be something like 5 metres higher than the sea.

The first Post in this Series is here. The Index to all the Posts in the Series is here.

Author: tumblestoneblog

Retired Academic, male, living in the New Zealand countryside near Whanganui with his wife as well as Jasper the dog, Fluffy the cat, Dancer and Penny, the horses, and a shed half-full of stones. Email john.tumblestone@gmail.com. View all posts by tumblestoneblog