Category: Gemstone Beach, Orepuki

This afternoon I spent two-and-a-quarter hours on Gemstone Beach with fellow rockhound Chrissy and her dog Ohla. We arrived just over an hour before low tide, easily avoiding the recent high levels of waves coming up the beach. At the start, the weather was the best of any day during my current trip, it being sunny with temperatures being around 17 degrees though with some wind. There were three cars in the car park when we arrived and a handful of people on the beach, one person being as far down as the Waimeamea River. We ourselves also made it to the Waimeamea though rain started coming down shortly after that. Halfway back to the car park, the wind came up, almost to gale strength, and the accompanying rain might have included some hail. The temperature dropped quickly to eight degrees. We were buffetted, cold and very wet during the last 400 metres or so.

Gemstone Beach stones.

Gemstone Beach stones.

The view westwards from the car park today.

The waves were still a bit wild today.

Looking back over the Taunoa Stream (middle distance) to the beach in front of the car park.

Chrissy and Ohla on the way to the Waimeamea River.

The mouth of the Waimeamea River.

A wave going up the Waimeamea River at its mouth.

But the stones were worth it. I saw a lot of trace fossil stones, quite a few interesting patterned stones, and the odd hydrogrossular garnet and poppy jasper. Below features 19 of my finds.

This find had the most interesting looking texture:

Other side of stone.

A stone with circular features in it – I have found two or three of these before on Gemstone Beach but am unsure of its identification:

A colourful breccia ( a stone consisting of angular, not rounded, fragments):

A different kind of breccia:

Sometimes I think this next kind of stone is also a breccia, consisting mainly of quartz plus epidote with maybe a little feldspar – but it could instead be a cluster of crystals:

An igneous stone with white crystals plus some intriguing orange circular features: 

Two different igneous stones with white crystals, probably diorite with feldspar crystals – the second one seems to include two different variations distinguished by the size and number of the white crystals:

A nice brown hydrogrossular garnet:

This is my favourite kind of poppy jasper: 

This second and much smaller small poppy jasper has small widely-spaced orbs/spheres and its silvery-grey hematite shows through well between them:

The following were among the diverse trace fossils in argillite stones I picked up. This first one has a large raised trace on one side while its other side is very different, seeming to contain many small faint traces:

Other side of stone.

Well defined slightly-raised traces: 

A long solitary trace: 

A faint but nevertheless recognisable trace:     

My favourite of today’s trace fossil stones, containing a couple of obvious large traces, some small traces, and three or four large faint traces – there’s a lot going on here:     

This the smallest of my trace fossil finds is also a favourite because its clearly defined traces cover around half of its surface:

When I saw this next stone, a red one, I wondered initially if it might be a breccia of some kind but close inspection of especially the longest of the lighter-coloured fragments (down its centre section) strongly suggests there are trace fossils too:    

Finally, I wonder whether the little central feature in this stone could be a trace fossil – it’s very unusual and shaped like some trace fossils I have seen:      

So it’s farewell to Gemstone Beach once again, my next fossick taking place on my drive north, at Kakanui’s Seadown Beach. An Index to all the Posts in this Series is here.

Note: This Post (and the rest of the Posts in this Series) is being published more than two weeks after it took place due to other things taking up my time recently.

Yesterday, on Thursday, I had a quick visit to Gemstone Beach in the late afternoon with my brother-in-law Ray. Unfortunately, the conditions were not good at all, with the waves coming high up the beach, the temperatures being cold, and rain starting to come down. 

Arriving at Gemstone Beach, Thursday.

Waves were coming high up the beach and rain was threatening.

Ray, a Southlander, in his shorts despite the low temperature.

There were a few other visitors there, and there were exposed stones in front of the car park. But we did not stay long, only a few minutes.

I returned to Gemstone Beach on the Friday, arriving earlier in the day at 11am when the tide was a lot lower. The only other person on the beach was one of the local part-time gold miners. The temperature was about 10 degrees with a cold wind and the occasional spot of rain but I was wearing warm waterproof clothing. I made it down to the Waimeamea River which was flowing out to the sea over the beach, preventing further progress.

Stones along the edge of the Waimeamea River.

On the northwest side of the Taunoa Stream.

Gemstone Beach when I arrived.

The notch in the cliff, 3/4 along towards the Waimeamea River, with a large tractor tyre washed up.

Looking back from close to the Waimeamea River Lagoon.

Driftwood packs the dry southern end of the Waimeamea River Lagoon.

Looking southeast from a small hill near the Waimeamea River Lagoon.

The Waimeamea River flowing across the beach to the sea.

 I was on the beach for just over two hours, and found a number of very interesting stones. Fourteen of them are featured below.

The most unusual and intriguing find today is this small stone – I don’t know what it is but find its complex texture attractive:

Other side of stone.

I collected three small poppy jaspers. The following are images of three sides of the first of them:

A second side of the stone.

A third side.

This is the smallest of the three but with well-formed “poppies”:     

Another side of the small poppy jasper.

The third one has the smallest “poppies”:

Poppy jaspers are composed of orbs or spheres, with the two terms used interchangeably, as in Mindat: “Orbicular Jasper is a name given to a highly silicified rhyolite or tuff that has quartz and feldspar crystallized into radial aggregates of needle-like crystals, forming orbicular (spherical) structures.” As Geologyscience puts it: “Orbicular jasper is a variety of jasper, a type of chalcedony, known for its distinctive orb-like patterns. These patterns can vary in size, color, and arrangement, creating unique and visually striking stones. Orbicular jasper often displays concentric circles, spherical shapes, or irregular spots resembling orbs, hence the name ‘orbicular’.” Some of the “poppies” in poppy jaspers I find on Gemstone Beach are tiny and don’t seem to have any internal structure – I tend to think of these as orbs. Other stones have “poppies” which seem to have a centre, sometimes of a different hue, and tiny radial lines, as in these three stones above – I tend to think of these as spheres. However, this distinction between orbs and spheres may just be my own concoction.

The next four stones are ones with hydrogrossular garnet in them. They all have the waxy feel associated with this type of stone. The first is the most translucent of the four, with a tint of grey, a few dark lines and some dark-coloured diopside crystals in it:   

The second is also at the more translucent end of the spectrum: 

The third is much more opaque, a nice orange colour:

The fourth has an interesting black and white character, and I lingered longest over its identification, wondering if it might instead be a form of quartz but deciding hydrogrossular garnet was the more likely:

Three argillite stones with well-defined trace fossils:

A banded argillite with an unusual top:

A stone that could be rhodonite, with its purplish-pink and black colouring:

Other side of stone.

This looks like it could be rhyolite:    

My next fossick will be the final one I undertake at Gemstone Beach this month. An Index to all the Posts in this Series is here.    

Chrissy and I and Ohla the dog spent a couple of hours on Gemstone Beach this morning. We arrived two and a half hours after low tide and would have spent longer there but the waves these days are coming quite high up the beach. With cliffs backing the beach, it is prudent to avoid the potential to get caught. It was warmer today, being about 14 to 15 degrees when we left around noon, and the wind was light. There was a good scattering of stones on various parts of the beach, including in front of the car park. There were also lots of interesting stones. Fifteen of my finds are featured below.

Chrissy and Ohla making their way along the beach.

Lots of stones further along the beach.

Scattering of stones in front of the car park.

Taunoa Stream today.

The waves were coming further up the beach than usual.

The most interesting stone I picked up was this one:

Another side of stone.

I thought initially this might be a rough hydrogrossular garnet. Looking at it a few times, I’m now wondering if in fact it might be chalcedony. Whichever it is, it is a nice size. [In October I tested the specific gravity of this stone – the result ruled out chalcedony and supported it as being hydrogrossular garnet.]    

This next stone could be rhodonite – it’s a gorgeous specimen:

Another pinkie, a possible thulite:

This fourth stone looks like it might have started out as a spotted argillite and then underwent some changes:

A couple more greenies:     

A porphyry, maybe feldspar in basalt:

A brown rhyolite, and a reddish stone with lots of little bits in it:     

Rhyolite.

This stone has an intriguing texture when viewed close up:

A kind of banded argillite:

The biggest of the trace fossil argillite stones I found today:    

The smallest of the trace fossils I collected:

The trace fossils in the next stone are also hard to see initially – they are faint and not as well defined. I particularly like the one running alongside the dark vein that makes its way up the right hand side of the stone:    

A more common, and much clearer, trace fossil argillite specimen:

The next Post is about a fossick on Papatotara Beach. An Index to all the Posts in this Series is here.    

Today’s fossick was partly prompted by a fellow rockhound turning up at Chrissy’s with an interesting blue stone. Michelle operates Deep South Pounamu (Mataura) and is a member of the Southland Geological and Lapidary Club. She had been looking for stones on Gemstone Beach with her daughter Amelia. They had found quite a few hydrogrossular garnets and, in the same spot, came across a small heavy blue stone that was unlike any hydrogrossular she had seen before. I took some photos but then accidentally deleted them. Michelle sent me these photos later:

Some hydrogrossular garnets found by Michelle and Amelia, with the blue stone in the centre. Photo by Michelle.

Could this be a Gemstone Beach sapphire? Photo by Michelle.

Close-up.

I noted at the time that the stone did not have the deep royal blue of the Gemstone Beach sapphires I had previously viewed. More on this stone at the end of this Post.

Prompted by Michelle and Amelia’s hydrogrossular garnet finds, Chrissy and I felt it would be a good idea to visit Gemstone Beach this afternoon. The weather was not the best. We arrived at 3pm in unpleasant conditions, just over an hour past high tide. The temperature was 12 degrees, there was a cold wind blowing, and storm clouds were overhead. There was a high swell and lots of foam on the beach. There were a handful of hardy souls there, including one of the local small-scale gold miners.

There were 3 or 4 people by the Stream With No Name.

A lot of foam was blowing about in places.

Chrissy and two other brave stone hunters.

The waves were too high to go past the Taunoa Stream.

The waves were sweeping in back and forth over a good patch of stones in front of the car park. We walked down to the Taunoa Stream but decided not to attempt a crossing – the stream was deep and swiftly flowing, and the occasional wave was coming in nearly to the foot of the cliffs. Sand had been deposited in this area and there were no stones to be viewed. So we went back and spent our time looking in front of the car park, often backing off from the higher waves. There were lots of interesting stones there. 

Overall, we collected some good specimens though we found very few hydrogrossulars. Ten of my finds are featured below.

One of the prettiest stones I found was a small amygdaloidal one:

Small amygdaloidal basalt.

Other side of stone.

Tiny holes originally filled by gases as the basalt was cooling have been infilled by colourful minerals such as zeolites. See “Z is for Zeolite” for more information  on amygdaloidal stones.

A dark red stone with lots of texture when viewed up close:

A nice small light-green quartzy stone, probably brecciated – I find these very attractive and interesting:

Next is a small stone with light coloured patches standing slightly proud against a dark red/purple background. When I picked it up, I could see tiny hints of green and light red:

An igneous stone with white crystals, this stone drew my eye because the crystals seemed especially bright:

For examples of variations of such stones, see Stones W43 to W63 in this Post. 

I picked up a stone that felt rough, like a sandstone. But its grains appeared to be larger than I expected. When photographed and zoomed in, you can see a fascinating bunch of teeny tiny fragments:    

I spotted quite a few trace fossil stones, a couple of which were unusual. This one in particular is very attractive. Its traces are the same colour as the host rock, and are particularly well defined:   

Two other argillite stones with trace fossils:

Some argillite stones have patterns in them that may or may not be trace fossils. Here is an example:

Argillite.

To return to Michelle’s blue stone mentioned at the start of this Post. She later send me the results of some testing she had just done, comparing it to three hydrogrossular garnets. She checked their fluoresence and specific gravity, and the blue stone’s hardness. Her concern was to see if the blue stone is a hydrogrossular or might in fact be corundum, the material that makes up sapphires.

Fluorescent stones glow in visible colors when exposed to ultraviolet (UV) light because certain trace inclusions absorb and re-emit the energy. Michelle has found that hydrogrossular garnets tend to look pink under uv light, something that Chrissy and I also observed when we visited Gemstone Beach one night with uv torches. This website suggests that only some hydrogrossular garnets fluoresce. Michelle found that her blue stone reacted very differently to uv light compared to her other three. She wrote in her summary of her testing: “Under the same UV light, Stone #1 [the blue one] showed little to no visible reaction, while the comparison stones identified as hydrogarnet showed a noticeable reaction.” From what I can tell online, blue corundum tends not to fluoresce. 

The specific gravity of a stone is its relative density, a measure of mass by volume. As one local website puts it, a stone’s specific gravity is the ratio of its mass to the mass of an equal volume of water. One way of calculating it is as follows: you weigh the dry stone, then suspend it completely in water sitting on a scale, and see how that changes the weight measured by a scale; you then divide the dry weight by the extra weight of the water in which the stone is suspended. The process and why it works keeps eluding me from time to time – I found this video useful:

Michelle used this method to calculate the specific gravity of her blue stone and the three hydrogrossular garnets. These are her results:

Michelle found her blue stone to have a higher specific gravity than the three hydrogrossular stones. Note that any or all of these stones could contain material other than hydrogrossular which will affect their specific gravity measure.

Generally speaking, there are accepted standard specific gravity measures for minerals. Corundum, for example, is said to have a very high specific gravity of 4.0, though Wikipedia notes that it can vary between 3.95 and 4.10. Quartz has a specific gravity of 2.65 and diamond is 3.5. A rock that is predominantly one mineral can have a little bit of other material in it, decreasing or increasing its specific gravity a little.  Most rocks are made up of two or more minerals and their specific gravity will vary depending on the precise mix. 

I did an online search for the specific gravity of hydrogrossular garnet. Wikipedia put it at 4.15 as did ChemEurope, but Gemology Project had it much lower, between 3.60-3.68, and Gemdat was lower still at between 3.25 to 3.40 – these lower measures are closer to the measures I have seen for grossular garnet. I’m not sure what accounts for these differences – gemologists may take a different approach than others. But it makes it difficult to interpret Michelle’s results. Although certainly the blue stone’s specific gravity is much lower than would be expected if it is corundum.  

For the hardness testing, Michelle scratched the blue stone with a steel knife, finding that the knife left a silver-coloured transfer mark on it but not an obvious groove. This suggests the stone is harder than the steel. Then she found that the stone left a scratch on glass. Thirdly, the stone produced a clear scratch in some crystal quartz – when the test was reversed, the quartz did not visibly scratch the stone but instead, the sharp point of the quartz became blunted/worn. So Michelle’s blue stone is reasonably hard. Hydrogrossular garnet is hard, so much so that Maori used it for hammer stones.

It’s clear from Michelle’s testing that her blue stone (Stone #1) has the highest specific gravity of the four, though the variation between the other three of 0.18 is the same as how much higher the blue stone is above Stone #2. The fact that the blue stone does not fluoresce is very suggestive that it is significantly different from the three hydrogrossular garnets. 

I am very impressed with Michelle’s testing and how she carefully recorded it. It is unfortunate that, it seems to me, there is some ambiguity about the standard specific gravity of hydrogrossular garnet, which is not helpful.

The next Post is about another Gemstone Beach fossick with Chrissy. An Index to all the Posts in this Series is here.  

I drove from Riverton to Orepuki this afternoon, arriving at Gemstone Beach at 3.30pm. I was on my way to visit Chrissy at Papatotara to see the newly arrived books “What’s This Stone?” and to discuss Thursday’s book launch. It was windy, about 14 degrees, with storm clouds in the near distance. It was a dull afternoon, not the best light conditions for looking for interesting beach stones. Two cars were leaving when I parked, and no-one else was around. There was a good patch of stones in front of the car park. They seem to have been freshly turned over, and a diversity of colour and pattern could be seen. I crossed the Taunoa Stream, noticing a recent slip in the cliff, and fossicked among a good scattering of stones along the beach to the northwest. 

A deserted Gemstone Beach, pre-storm.

The crib in the cliff.

The Taunoa Stream.

Slip on other side of Taunoa Stream.

Stones along the beach on the other side of the Taunoa Stream.

Next photo zooms in on a stone showing a reflection of the photographer.

There had been some cliff crumbling there as well, and sand had been shifted, exposing some of the orange sandstone platform that seems to underlie the beach. Some soft iron-stained stones had come out of the cliff.

Exposed platform of orange sandstone.

Patterns in the sandstone.

Cliff erosion.

Iron-stained stones from the cliffs.

I turned around after about 400 metres from the stream. Then a fierce southerly storm hit me – high winds and blinding cold rain with some hail in it. I was caught in the open. Fortunatelt I had a good rain coat on, but my jeans were drenched below my knees and water trickled into my gumboots. I struggled across the Taunoa and sheltered for a few minutes next to the crib in the cliff before making a break for the carpark, about 200 metres away. The temperature had dropped to 7 degrees, probably around 4 or 5 degrees with the wind chill. Was it worth it? Of course! Here are 11 of my finds.

The most interesting is perhaps this small dark red jasper which on close inspection seems to be a variety of poppy jasper:

Other side of stone.

Another intriguing small stone, with fuzzy-edged crystals:   

Two brown stones, maybe sugar quartz, variations of darker and lighter:    

I found a few argillite stones with trace fossils in them. This first one is packed with strongly expressed relatively large traces, with a couple of smaller and brighter ones overlying. I took it along to Thursday’s meeting of the Southland Geological and Lapidary Club and entered it into the night’s competition for recent finds.   

Trace fossils in argillite.

However, there were three or four other very interesting entries which attracted all the votes.

This second trace fossil stone has green traces:   

Argillite with trace fossils.

The third is a more common combination of colours, and contains quite a few traces, many cnsisting of lines of chevrons:    

Another argillite stone with trace fossils.

I continue to be fascinated with the variations of dark igneous stones with white crystals of different shapes, sizes and proportions. Here are four I picked up today:   

My next fossick takes me back to the Beach Beach at Riverton Aparima.    

An Index to all the Posts in this Series is here. 

On Monday and Tuesday this week, Chrissy and I worked on our book “What’s This Stone: A Photographic Collection of Finds From Gemstone Beach”. I then got sick on Wednesday with a bad cold initially combined with a migraine. On Thursday, despite my condition, we managed to finish a complete draft of the book. We then did some checking, editing and layout tweaks on Friday and Saturday. Chrissy has worked long and hard to wrestle the pages into shape. The book draft is now being checked and proof-read by others. On Sunday Chrissy and I went for a fossick on Gemstone Beach, reported below, and the next day I packed up to head back north after watching the World Cup football final, the last half-hour with Mike.   

Current cover of draft book.

Contents page.

First page of a stone entry. With a spelling error in the title!!

Shaking map for Thursday night’s earthquake. Source: http://www.geonet.org.nz/earthquake/shaking/2026p530771

The other happening this week occurred on Thursday night, when an earthquake produced a long period of rocking. It was one of the biggest quakes felt in the south for a while. The magnitude 5.9 event was located about 40 kilometres north of Te Anau, which is about 140 kilometres north of us. A tsunami warning was issued but later withdrawn, This was another reason to stay away from the beach for at least a couple of days.

Chrissy and I arrived at Gemstone Beach at 11.30 am, the temperature being nine degrees. There were five cars and one campervan in the carpark. The earthquake-agitated sea had wrought some changes. The sand in front of the carpark along to the Taunoa Stream was very smooth and rose subtly but consistently to the back of the beach in a way I had not noticed before. Across the Taunoa Stream, sand had been removed so that the previously noted three patches of stones (described here) had expanded by maybe five or six times. And the mix of stones was greater, with quite a few interesting ones among them. We spent two hours on the beach, mainly in this area, deciding not to walk all the way down to the Waimeamea River. We found a handful of good hydrogrossular garnets. I came away with 66 finds in all.

The beach in front of the carpark.

Looking back towards the carpark.

The view towards the carpark from just over the other side of the Taunoa Stream.

One of the greatly expanded areas of stones on the other side of the Taunoa Stream. Another fossicker coming our way.

Looking back from the first large patch of stones.

Chrissy in the distance.

My 66 finds from today.

Chrissy found the best hydrogrossular garnet, just as I was chatting with people who wanted to touch one to feel its waxiness. It’s a large brown one with flashes of white, and I photographed it on the beach:

Chrissy’s brown hydrogrossular garnet.

Other side of Chrissy’s brown hydrogrossular garnet.

The best three that I found included a green partly transparent one:    

Hydrogrossular garnet.

and a white one with a clear band:    

Hydrogrossular garnet.

and this light tan partly transparent one:  

Hydrogrossular garnet.

I came across a large argillite stone with trace fossils in it. It’s such a good speciment that I decided to put it in my bag – it’s can be used to show what these stones look like in the rough:

Large argillite stone with trace fossils.

A small banded argillite with a kind of “glazed” surface:

Banded argillite.

A different type of banded argillite which seems not to have been as “baked” as the previous one:

A type of banded argillite.

A small green stone with lots of interesting detail:

Other side of stone.

A small brecciated quartzite – I really like the kind of pattern to be seen in its top left quadrant:

The next small stone looks to be brecciated but I’m not sure if it’s a quartzite or  jasper – it certainly has bits of quartz in it but it could be part of the matrix. Its light and dark colours make it really attractive:

Other side of stone.

Three more red ones with interesting bits, the second with an especially fascinating vein:

I thought I had found a small piece of petrified wood, a rare event on Gemstone Beach, but after closer examination I think it is more likely some kind of sedimentary stone, probably a mudstone:  

This was a good fossick to end my time here. Many thanks to Chrissy and Mike for looking after me so well during my stay at their place in the south.

The next Post in this Series describes some finds from Kakanui’s Seadown Beach. An Index to the Series is available here.    

The day after the rather intense Southland Geological and Lapidary Club’s Show/Open Day, Chrissy and I headed out to Gemstone Beach for some fresh air and recreation. It was nine degrees and sunny when we arrived there at 2.30pm. Sixteen cars were in the carpark and lots of people were on the beach, though only one had ventured beyond the Taunoa Stream.

A busy beach, when we arrived.

Looking back shortly after we arrived.

When we returned two hours later, still a lot of people on the beach.

We spent just over two hours, walking down to the Waimeamea River and back. Normally it would have taken us a lot longer but the large areas of sand meant we made quick progress most of the time. 

Featured below are eight of the stones I collected this afternoon. The first is a dark red hematite jasper, the hematite being the silvery material within it:

Hematite jasper.

I found an amygdaloidal stone, possibly a basalt. Small gas bubble holes in it have been filled with a white mineral, maybe quartz:

Amygdaloidal stone.

For information on amygdaloidal stones, see Section 4 in this Post.

Next are two trace fossil stones. The first has some strong traces running along the surface, the second smaller stone has just one trace, a burrow emerging from within: 

Trace fossils in argillite.

Small argillite stone with a small trace fossil.

This much larger stone is a spotted argillite that may include some red trace fossils:

Spotted argillite, with trace fossils?

For more information on trace fossil stones in argillite, see Stone #10 in this Post.

An interesting little argillite that shows some displacement within it due to tectonic stress, called by some an earthquake stone:

Argillite earthquake stone.

I’m not sure what kind of stone this next one is, but I like the various tiny shapes it contains:      

Finally a small green stone with some subtle changes of hue within it:     

The coming week will be busy working on the completion of the final draft of the photo book on Gemstone Beach stones that Chrissy and I are producing.  

The next Post in this Series is about my final Gemstone Beach fossick for this trip, which took place a week later. An Index to the Series is available here.