Month: May 2026

I gifted 50 polished stones found on Kai Iwi Beach, near Whanganui, to Cam who sold me some books at a good price. Many of the stones I gave to Cam are some variety of quartz, the predominant type of stone on Kai Iwi Beach. Part One describes the background and the first ten stones.  This Post describes another ten of these stones.

Stone 11  again consists primarily of quartz, with only a light sprinking of iron oxide in it. You can’t see many quartz crystals in it due to their tiny size and tight compaction:

Stone 11.

Other side of Stone 11.

By contrast, Stone 12, another quartz, has hardly any iron oxide in it and some small clear quartz crystals are much more obvious in it:

Stone 12.

Other side of Stone 12.

In Stone 13, the iron oxide is laid down across only part of the stone so that where it is absent appears as white bands of varying width:    

Stone 13.

Other side of Stone 13.

Stone 14 is what I call a “two-sider” – the two sides differ enough from each other that you could be forgiven for thinking they might belong to two different stones. The main difference is the absence or presence of yellow:   

Stone 14.

Other side of Stone 14.

I am not sure what type of stone is Stone 15. It’s not the usual iron oxide-stained quartz. It contains a mineral that gives it a green hue, and the rectangular-like crystals in it are probably not quartz but are more likely plagioclase feldspar, another very common rock-forming mineral:

Stone 15.

Other side of Stone 15.

Stone 16 is a small dark red jasper. Jasper is a type of chalcedony or microcrystalline quartz, a dense aggregate of microscopic quartz crystals too small to be seen with the naked eye. It is opaque due to the presence of minerals which give it colour, with the red of iron oxide being most common. Jasper is usually classified as sedimentary, precipitating from solutions moving through the ground.   

Stone 16, jasper.

Other side of Stone 16.

The stone could be called a “brecciated” jasper, having been fragmented to some extent by tectonic stress. The small areas between the fragments have become veins as they have been filled by mineral. The larger veins contain some white quartz, stained yellow/orange. The many fine veins in the stone have been filled with a clear mineral which could, again, be quartz. “Brecciation” has previously been explained in relation to Stone 2 (see Part One).

Stone 17 is a white quartz – you can see tiny clear crystals in the close-up photos which are embedded in a “frothy” white quartz mix, likely to contain water and/or air: 

Stone 17, quartz.

Other side of Stone 17.

It is similar to Stone 12 (above, earlier in this Post) but the shape and distribution of the tiny clear crystals is a bit different.   

Stone 18 has some similarities to Stones 4 and 9 (see Part One), consisting of white, yellow, brown and black crystals:

Stone 18.

Other side of Stone 18.

The white is quartz, the yellow and brown is iron oxide, and the black (sometimes sparkly) will be mica.

 Stone 19 has an unusual black patterning on it, one that caught my eye on the beach:    

Stone 19.

Other side of Stone 19.

Again the stone is quartz with some yellow/orange iron oxide, but I am unsure what the black mineral is.

Stone 20 is completely black:

Stone 20.

Other side of Stone 20.

There are a few tiny light areas on each side of the stone, hinting that it is quartz that has been flooded by a black mineral. I used photo software (Picasa 3) to lighten the close-up images to reveal some of the subtle patterns on the stone’s surface – on the left are the original images, on the right are the lightened ones:

Part Three, Stones 21 to 30, is not yet available.  

Recently I was wanting to buy some books on Scottish Island knitting patterns on behalf of my wife. I inquired at my favourite local secondhand bookshop, Book Hunters on Ridgway Street in Whanganui. There I spoke to Cam who said they had none in stock but he would look out for them, and he wrote my contact details in his book. Not long afterwards, he rang to say he had found a bunch. They were just what I was after, and he gave me a good deal on them. I knew he lived at Kai Iwi Beach so I asked whether he would be interested in a gift of some tumble polished stones from there. He said yes, so I have picked out 50 to give to him. 

Kai Iwi Beach is my local beach and from time to time I walk Jasper the dog there. There are not many stones on that beach – in fact, the area is much better known for fossils, especially of moa. The nearby village is called Mowhanau and it is thought the name could have originally derived from “moa-whanau”. I automatically look for stones when I am on any beach. As a result, over the past few years I have collected quite a few from Kai Iwi Beach that I have gone on to tumble polish. Most of them are quartz that have been stained yellow-orange by iron oxide – see “The Iron-Stained Stones of Kai Iwi Beach”. A few other stone types occur, and I recently found a trace fossil in argillite and an orbicular jasper, both rare. With even ordinary appearing stones, however, when they are viewed up close, there is quite a variety of interesting colours and patterns in them.   

Jasper on Kai Iwi Beach.

Second hand books from Book Hunters.

Fifty polished Kai Iwi Beach stones.

Some of the stones.

 The 50 stones given to Cam are presented in this series of Posts in no particular order. The first ten are below.

 Stone 1 could be mistaken for a jasper, given its red hues. However, it is more likely to be quartz with its colour due to the presence of iron oxide:     

Stone 1, a type of iron oxide-stained quartz?

Other side of Stone 1.

Quartz is one of the most common minerals on Earth and is hard and glassy. Its purest form is rock crystal which is colourless and transparent. However, more often quartz stones incorporate other minerals which give them colour and make them opaque. Iron oxides include a number of chemical compounds such as hematite and limonite. They can colour stones a number of hues, from yellow to orange to red to brown and even black.

Stone 2 could be a mudstone because of its very fine grained and smooth character. Mudstone is a sedimentary rock, often laid down on the ocean bed. But what is most interesting about Stone 2 is that it has fragmented in places due to tectonic stress. Great weight of rock can move slightly and deform or break-up what lies beneath. The fragments in Stone 2 are angular which means the stone could be viewed as a kind of breccia – see “T is for a Type of Tiny Tectonic Breccia?”   

Stone 2, brecciated mudstone?

Other side of Stone 2.

Stone 3 is more typical than Stone 1 for the kind of iron oxide-stained quartz from Kai Iwi Beach, being more orange-yellow in colour. It is more spherical in shape than most of the stones on the beach which tend to have two distinct flat sides:    

Stone 3, typical Kai Iwi Beach iron-stained quartz.

Other side of Stone 3.

Stone 4 is made up of lots of tiny bits of quartz and other minerals. It could be a kind of sandstone, formed from the compaction of these tiny bits, though most sandstones have finer grains:     

Stone 4.

Other side of Stone 4.

Stone 5 is another iron oxide-stained quartz but the mineral is distributed within the stone quite differently from Stone 3, with the quartz itself sometimes showing white around the edges: 

Stone 5.

Other side of Stone 5.

Stone 6 appears in some ways to be a more compact version of Stone 4, made up of lots of tiny bits of quartz with iron oxide providing a yellow-orange colour: 

Stone 6.

Other side of Stone 6.

Stone 7 is again likely to be made up primarily of quartz but there is a black mineral in it providing a different character to the previous stones:

Stone 7.

Other side of Stone 7.

Some stones look different on different sides. Stone 8 is an example of this. Again, it is an iron oxide-stained quartz, similar in many ways to Stone 5, but the distribution and pattern of the colour-providing mineral varies a lot on the two different sides:    

Stone 8.

Other side of Stone 8.

Stone 9 has some similarities to Stone 4 but has more small dark mineral bits in amongst the tiny quartz crystals. I suspect some of the dark bits are biotite mica, which also sparkle when they catch the light just right:    

Stone 10, the final one in this Post, is again an iron oxide-stained quartz. Some areas of the stone have no colour-providing mineral in it and it seems as though you can see into the quartz to some extent:  

Stone 10.

Other side of Stone 10.

Stones 11 to 20 are described in Part Two.  

Currently I am spending most of my time working on a photo book on Gemstone Beach stones. At this stage, I have collected together photos from the last four years and drafted text for entries on 20 diffferent stone types. I am just finishing writing six sections for the Introduction. I next need to edit some of the text I write earlier, to improve it. Chrissy is working on the layout, and we will eventually need to get together to finalise things.

But I am also finding the opportunity to tumble some stones, including this Kai Iwi Beach one. I found it about ten weeks ago and think it is probably an orbicular jasper – see this Post. I have recently tumbled it in 400 grit for 11 days and then in 600 grit for 10 days. It has come out nice and smooth, ready to go to a final polish stage. When found, the orbs in the stone were raised, suggesting they are harder than the rest of the material. I wasn’t sure if tumbling might not produce a completely smooth surface, but it has. Following are photos of the stone as found (below, left) followed by the stone after tumbling to date (on the right):

Stone when found.

Stone after 400 and 600 grit tumble.

Stone when found.

Stone after 400 and 600 grit tumble.

Stone when found.

Stone after 400 and 600 grit tumble.

The orbs have an interesting structure and are nicely defined. I am pleased with progress so far and look forward to seeing what it looks like when polished.