Some More Polished Gemstone Beach Stones for Michelle

I recently tumble-polished a batch of 51 Gemstone Beach stones for Michelle, in a 3lb barrel – see this Post. A second 3lb barrel has now been finished, this time with 60 stones as some of them were smaller:

This Post features 14 of these 60 polished stones.

Michelle likes to spend time on Gemstone Beach, often alone, bent over and looking through the many pebbles there, putting her finds into a bag to take home. She refers to herself as a stone fanatic, but she’s not alone. The Introduction to a book entitled “Beach Stones” (published in USA in 2006), by Josie Iselin (photos) and Margaret Carruthers (text), starts as follows: “What compels us to walk along the beach, our gaze fixed upon the sand? We can’t resist the smooth, surf-polished stones that have been tossed this way and that by the waves. Their intriguingly varied colors, patterns, and shapes draw us to the hunt, and soon our hands and pockets [and bags!] are full. Something about beach stones is comforting. They don’t age, die, or fade away.” Beach stones don’t demand anything from you, except your appreciation. And when you are surrounded by stones on the beach, out in the natural environment, away from other people, it is also grounding, stimulating and healing. A time to oneself. As I wrote in a previous Post “Somewhere In-Between”, describing being on Gemstone Beach, hunting for stones: “[There I was,] fossicking on a beach between the powerful waves and the high cliffs, with the intermittent concussion of the booming breakers roaring across banks of stones, …encountering the rawness of the sun and wind and rain, with the thin sharp cries of seabirds somewhere in the distance. The beautiful and the vast.”

That book, “Beach Stones” by Josie Iselin and Margaret Carruthers, features many beach stones, usually accompanied by notes on what kind of stone they are and where they came from. Interestingly, one of their stones, which came from San Francisco, is the same kind as one of Michelle’s Gemstone Beach stones in this batch. They refer to its “white feldspar crystals”.

I have picked up this sort of stone before, on Gemstone Beach and elsewhere along the southern coast. It’s a kind of porphyry, a stone having relatively large crystals, and it’s maybe basalt. I’ve always wondered what the light-coloured crystals are. Now I know they are feldspar. Michelle’s find also has a light blue tinge to it (to my eye):

Some feldspar is white, known as plagioclase feldspar, but another common form is a pinkish orange known as orthoclase feldspar. It can be seen in this stone I also polished for Michelle:

The green mineral in this stone is likely to be epidote. This means the stone can be called “unakite”. Geology.com states: “Unakite is a pink and green metamorphic rock composed of pink orthoclase, green epidote, and colorless to milky quartz… Unakite forms when granite is altered by hydrothermal fluids, and plagioclase in the granite is transformed into epidote.“ The next three stones, all small, also contain feldspar and epidote, though ranging from quite light hues to much more intense:

Sometimes the orange in a stone will be due to the presence of iron oxide, as is the case I think with these next two:

The eighth stone in this Post is a two-sider – each side is quite different from the other. The first side has a lot of white; the second side includes some iron oxide:

The next stone is a mudstone breccia. This means it consists of a number of small angular fragments of mudstones, cemented together in a fine-grained matrix:

These can be difficult to tumble polish as some of the fragments may not be as hard as others and may not become shiny. The tenth stone is another breccia, but this time with larger fragments. There are some green epidote crystals in it as well:

And here is another two-sider, with some tiny brecciation on the first side. In this case, probably tectonic stress has crumbled the stone and water has flowed through it, leaving quartz to hold it together:

The dark red/purple areas in this above stone is likely to be a more concentrated form of iron oxide. You can see this in the twelfth stone too:

All of the stones we have looked at so far have been opaque. In terms of the ability for light to pass through stones, there are three main types. A “transparent” stone is one that light passes through easily, as through a glass window. A “translucent” stone is one that only limited light is able to pass through, so that an object held behind it would look fuzzy. An “opaque” stone contains minerals that do not allow light to pass through it at all. The next stone is a translucent quartz, with some minor mineral inclusions. Holding it up to the sky, you can see into it and, in places, through it:

The Post “Gemstone Beach and its Stones: An Introduction for the Passing Motorist – Part Five, Translucent Stones” contains a wide range of other examples.

Finally, a hydrogrossular garnet which is opaque although you can kind of see into it a little – it seems to have small two-dimensional clouds just under its surface. These garnets always tumble-polish well, coming out very smooth and shiny:

Time to send these stones back to Michelle.