“Beach Stones” by Josie Iselin and Margaret Carruthers (2006)

This is a book celebrating the beach stone in its raw form. Josie Iselin is a photographer and installation artist from San Francisco. She has published seven books which focus on those forms in nature that can be found “at hand” and, in particular, at the beach. She explains in the “Artist’s Note” on page 139 of “Beach Stones”, about ten years previously she abandoned her camera and instead started to use her flatbed scanner to gain a different level of detail in her images. All the pictures of stones in this book are scanned. Margaret Carruthers is an Earth Science writer from Baltimore and confesses to having “a vast collection of rocks” (dust jacket). Among her other books is the co-authored”National Audubon Society First Field Guide to Rocks and Minerals” (2005).

“Beach Stones” is a reflective rather than an investigative work. Stones are objects of intrigue and contemplation. The book collects stones from around the world, including a pair from Greymouth in New Zealand. One review expressed disappointment with the book in that there was not enough information of each stone. But that is not its aim. Its aim is more to get the reader to “really look” at the stones, as Josie has done, and to speak of them in a way that arouses curiosity and leads to further personal engagement with beach stones.

 Physically, the book is 18 cm by 18 cm, consisting of 144 pages. Pictures of stones make up just over half of the book, and many of the pages of text contain just a few lines – the images of beach stones are its preoccupation. It is not expensive (Fishpond.com in New Zealand has it for sale at just under NZ$30). Every now and again, I enjoy spending time with a stone or three from its pages.    


Second Batch of Stones Taken to Final Stage of Polishing

These stones were picked up from Riverton beaches in February this year (2016). After about five weeks of tumbling, with careful sorting to weed out stones that would not take the polish effectively, this is the result – 58 stones of various sizes, shapes and colours. One could be an agate, I think, a rarity from Riverton beaches. But it might instead be quartz.

Polishing Agates from Birdlings Flat: Stage One

I found a small number of agates at Birdlings Flat and was given a number more by people I met on the beach. I have now tumbled these for one week in 100-mesh silicon carbide grit (see the bottom of this Post for an explanation of what agate is). The interesting results are as follows: 

The Gitche Gumee Museum is a rock and mineral museum in in Michigan. Its website has the following explanation about agate and its formation:

“Agate is a form of chalcedony, which is silicon dioxide in the form of microscopic fibrous quartz crystals. Agates naturally develop when an empty pocket inside a host rock, usually volcanic lava,  fills in molecule-by-molecule, layer-by-layer, as these microcrystals form concentric bands or other patterns. The colors and arrangement of the microcrystals are influenced by changes in pressure, temperature, and mineral content that occur during the formation process. The empty cavities and seams filled with fluids rich in dissolved and suspended quartz molecules (silica), as well as other mineral impurities. When the silica concentration became supersaturated, it developed a gelatin-like consistency either throughout the pocket or in a layer that served as the active crystallization front. Over time, the silica molecules began to form miniature fibrous microcrystals that attached to the sides of the cavity or seam. During the filling-in process other mineral impurities collected at the inside of the chalcedony silica band, forming intervening and often contrasting bands.” 

Wikipedia puts it like this:

“Most agates occur as nodules in volcanic rocks or ancient lavas, in former cavities produced by volatiles in the original molten mass, which were then filled, wholly or partially, by siliceous matter deposited in regular layers upon the walls. Agate has also been known to fill veins or cracks in volcanic or altered rock underlain by granitic intrusive masses. Such agates, when cut transversely, exhibit a succession of parallel lines…giving a banded appearance to the section. In the formation of an ordinary agate, it is probable that waters containing silica in solution – derived, perhaps, from the decomposition of some of the silicates in the lava itself – percolated through the rock and deposited a siliceous coating on the interior of the vesicles. Variations in the character of the solution or in the conditions of deposition may cause a corresponding variation in the successive layers, so that bands of chalcedony often alternate with layers of crystalline quartz.” 

Birdlings Flat Stones After First Stage of Polishing

These stones have spent one week in a tumbling barrel with 100-mesh silicon carbide grit. This first stage of the tumble-polish process removes the weathered outer layer of the stone and brings out its colours more clearly. Many of these stones will be quartzites.


My Visit to Birdlings Flat, Day 2: Stone Collecting

I bought some stones from Vince Burke at the Gemstones and Fossil Museum. I normally only like to collect what I find but there are special exceptions – and the Museum is a special place. Vince threw in some extras as well, so I came away with two rock agates from the Woolshed Creek area near Mt Somers, three large agate stones from Birdlings Flat, and some petrified and agatised wood from the Hororata River area. 

But my main purpose that day was to find stones of my own that I could polish. So after I had visited the Gemstone and Fossil Museum, I spent about 2 1/2 hours on the beach, concentrating my time on the northern end, walking all the way to the cliffs. The wind was much stronger, but down near the waves was the lowest part of the beach and somewhat sheltered from the north-wester. There were slightly more people around this day than the previous one – mainly fishing and, like me, hunting for stones.

I chatted with three people. Charles came from Christchurch and had been interested in stone collecting for just a couple of months – he had a friend who polished stones but did not himself have a tumbler. Charles was nearing retirement age, like myself. He explained to me that he was mainly looking for agate stones – he gave me some he had found. I had not developed the eye to find them as they are rather plain looking and I tend to seek out colour. As we talked, Charles said, “Oh look, there’s one!” and he stepped a metre away to pick up a small agate. And a minute later, he spotted another one not far away.

Later I ran into a woman who I found out was the daughter of Vince Burke, the Museum man. She was also out looking for agates and generously gave me a handful. Later still, I encountered a local on his afternoon walk who told me a bit about the beach and its dangers. “It’s a killer beach”, he said. The waves can be treacherous, coming in further and more quickly than one anticipates – turn your back on them to your peril. And it gets deep quickly off shore – people who go in after their dog can get into trouble. He also gave me a few agates he had collected that afternoon. 

I reached the cliffs at the north end of the beach but did not linger there. Charles had explained that one of the Christchurch area earthquakes had brought down part of the cliff-face. I had experienced a small but distinctly-felt earth tremor the night before in Christchurch and I was uneasy to focus too long on the stones at my feet when a mass of over-hanging cliff loomed above. 

I collected somewhere between five and six kilograms of stones that day, to add to the eight kilograms from Day One. That evening I packed them carefully into both my cabin baggage and checked baggage for my flight the next day back to Hamilton. Heavy bags!

My Visit to Birdlings Flat, Day 2: Gemstone and Fossil Museum

On my first day at Birdlings, I had seen the sign for the Museum so decided to visit it at the start of Day 2 of my visit. I had seen references to it online, where it was described as a private rock collection open to the viewing public.  One community information site added: “The display is mostly Canterbury material gathered from the rivers and hills, agate, quartzite, jasper, petrified woods etc, of which after many years would have all ended up on the beach at Birdlings Flat.” Another site stated:  “The Gemstone and Fossil Museum was opened in February 2003 by Vince and Colleen Burke and their children, who collected the many kinds of gemstones off Birdlings Flat Beach over 34 years. The collection has grown to include fossils collected since 2002, mostly from Amberley Beach to Kaikoura.” Vince is quoted in a 2012 North & South article on the Little River area as saying, “My wife wanted me to get everything out of the lounge” when they decided to live permanently at Birdlings Flat, sometime after his retirement as a builder in 2003.

The Museum is located at the end of Hillview Road at Birdlings Flat, a narrow road crowded on both sides by holiday homes and residences. Going in the gate, I found myself in a large courtyard to the left of which was the Museum building. A sign said to blow the horn on the wall, so I did, and Vince appeared and opened up. Inside is possibly the best laid-out and presented display of rocks and fossils that I have ever seen, a testament not only to the Burke family’s passion for stones and fossils but also to Vince’s intelligent ordering and labeling of the material being presented.

My favourite corner contained the petrified wood, agates and quartzites.

Petrified wood:

Agate stones:

Quartzite and rhodonite:

Perhaps more than half of the displays are of large colourful agates, most of them found by Vince himself in different parts of Canterbury:

One wall has a display of agates and rocks from different parts of New Zealand. Entry to the Museum is free, though donations are welcome, and you can purchase your own stones, rough or polished, to take away with you:

Vince graciously showed me around and shared some of the stories associated with various stones, especially the large colourful agates. He helped me to identify some of the stones I had been collecting recently. I bought some petrified wood and agate stones on the way out, and Vince then showed me around his workshop which contains his large homemade tumblers, vibratory vats, and cutting saws. All in all, an overwhelming and amazing experience.

Birdlings Flat Gemstone and Fossil Museum is open every day, 9.30 am to 5 pm, except when Vince is away rockhounding.