I have written a number of Reviews for “StoneSpeak”, the Newsletter of the Southland Geological and Lapidary Club. An Index to them can be found here. For the most recent (October 2026) edition of “StoneSpeak”, I contributed this piece which is more of an Article than a Review. It is a revision and expansion of a Blog Post “What is Hydrogrossular’s Place Among the Thirteen Minerals First Described From New Zealand?” that I wrote seven years ago (which contains photos of all of the first 13 minerals, if you’re interested). The version of the Newsletter Article that I have posted below has also been slightly edited, especially the second of the two paragraphs on hydrogrossular garnet, and a number of photos have been added. The Southland Club’s website is here and its Facebook Page is here.
As someone who spends time on Gemstone Beach, I have become very interested in hydrogrossular garnets. It takes a while to learn to identify these heavy shiny waxy stones, especially to distinguish them from quartz. Hydrogrossular garnet turns out to have an interesting New Zealand-related history, as I found out while doing research on it. Hydrogrossular garnet was first identified as being a variation of grossular garnet by Colin Hutton in the 1940s. Hutton, from Dunedin, worked for the New Zealand Geological Survey as a mineralogist. During World War Two, he examined a lot of geological material from South Island beaches, identifying a number of rare minerals, including the radioactive thorium mineral that was later named huttonite. He also identified the mineral hydrogrossular garnet as a major constituent of a Nelson rock that had been named rodingite after the Roding River in that region. See here for an account of Hutton’s life.
A mineral is usually defined as a naturally occurring, inorganic solid substance that has a fixed chemical composition and an ordered internal atomic structure. To put it another way, a mineral is an element or a chemical compound that is normally crystalline and that has been formed as a result of geological processes. Every mineral has a “type locality”, the specific place where it was first discovered, defined, and scientifically documented. However it can usually be found elsewhere as well and often in greater amounts. The International Mineralogical Association (IMA), founded in 1958, keeps a list of over 6,230 officially-recognised minerals compiled by its Commission on New Minerals, Names and Classification.
In the course of my research on hydrogrossular garnet, I came across Simon Nathan’s article in Te Ara, The Encyclopedia of New Zealand, outlining 13 minerals that had their type localities in New Zealand, having first been identified here. Simon Nathan (photo below, second row) started out as a geologist and became a science administrator before he started to write about the history of New Zealand science. One of his books is “Harold Wellman, A Man Who Moved New Zealand” (2005). Wellman, who died in 1999, was a geologist who in 1940 first identified the South Island’s Alpine Fault, partly due to the similarity of rocks in Southland and Nelson on either side of the faultline. Nathan also published “James Hector: Explorer, Scientist, Leader” (2015). In the 1860s, Hector (photo below), a Scotsman, was the first geologist to examine the rocks of Otago and Southland, exploring and mapping a huge area. He moved to Wellington to set up the New Zealand Geological Survey and Colonial Museum in 1865. As well as writing these and other books, Simon Nathan between 2004 and 2007 assisted with the science content of Te Ara, producing over 200 articles for it. One of those was on the minerals first identified in New Zealand, from which the following information is mainly taken. I have also added two more, for reasons set out at the end.
Of the 13 minerals that Nathan lists as first identified in New Zealand, seven of them have been named after a New Zealand place or region. First, “taranakite” is a fine-grained cream-coloured phosphate first described in 1865 by James Hector (NZ’s leading scientist at the time) and William Skey (an analytical chemist). It was named after the Province of Taranaki as it was first found on small islands near New Plymouth. Second, “awaruite” is a natural nickel-iron alloy, first described in 1885 by William Skey. It had been obtained from gold miners south of Haast on the West Coast of the South Island, around the Gorge River, and was named after nearby Awarua (also known as Big Bay). It was by electron micro-probe analysis of awaruite in the 1960s that another mineral, “wairauite”, was identified. This was announced in 1964 by two mineralogists who worked in the Department of Mineralogy and Petrology at the University of Cambridge, England. It is a natural cobalt-iron alloy and is the first mineral in New Zealand discovered by electron micro-probe analysis. Wairauite occurs as microscopic, scattered grains in serpentinite, often alongside awaruite, the grains rarely exceeding 5 microns (0.005 millimetres), so electron micro-probe is the only way to see it. It is named wairauite as the grains initially analysed were found in the Red Hills serpentinites of the Wairau Valley in Marlborough.
To now go back to the 1930s for the discovery of another mineral named after a New Zealand place: “Tuhualite”, a violet crystal that is unique to New Zealand (photo below), was first identified by geologist Patrick Marshall (photo also below) in 1932. He had found it on Tuhua/Mayor Island in the Bay of Plenty, its only source. The next mineral was identified in the 1950s. “Wairakite” is a colourless to white crystal found in geothermal environments. A zeolite, it was discovered and named in 1955 by Alfred Steiner, a pioneer geothermal scientist originally from Czechoslovakia. He had found it while examining hydrothermally altered drill cores at Wairākei. Sixth, “akatoreite”, a fibrous yellow-orange to orange-brown mineral, was recognised by Peter Read and Tony Reay (geologists from Carleton University and the University of Otago respectively). It is a previously unknown manganese silicate mineral. They reported in their 1971 publication that the mineral was found in a manganese-rich patch of chert and carbonate on the South Otago coast, three kilometres south of the mouth of the Akatore Creek, about 12 kilometres east of Milton.
In 1941, John Bartrum, a Professor of Geology, came across an unusual mineral on Motukorea/Browns Island in the Waitematā Harbour, that he called “beach limestone”. What eventually became “motukoreaite”, our sixth mineral, is a poorly cemented fine-grained calcareous rock. It was not officially described and named as motukoreaite until 1977 in an article in “Mineralogical Magazine”. It occurs as a boxwork of tiny crystals, each about 3 microns (0.003 millimetres) across. The crystals are semi-transparent and are white, pale yellow, pale yellow-green, or colourless. Wikipedia notes that a study in 1989 suggested that motukoreaite is a common, widely occurring mineral arising from the alteration of basaltic glass to calcite.
Two of Nathan’s 13 minerals first identified in New Zealand are named after people. First, “huttonite” (photo below) is a radioactive cream–coloured crystal, first discovered in beach sands from the West Coast by Colin Hutton in the 1940s who sent it to Adolf Pabst, an American mineralogist, to analyse. It was first described in publication in 1951 by Pabst who named it in honour of Hutton. It is most prevalent in the sand at Gillespies Beach, near Fox Glacier. Second, “coombsite” in 1991 was named in honour of Douglas Coombs, Professor of Geology at the University of Otago. This mineral consists of tiny brownish-yellow fibrous crystals. They were found in brown patchy aggregates from a small area of manganese-rich rock at Watsons Beach on the South Otago coast (only about 3.5 kilometres south of where akatoreite is found). Two Japanese mineralogists, Teruhiko Sameshima and Yosuke Kawachi, discovered this new manganese mineral and described it in 1991. Coombsite is very rare and has been found in only three localities worldwide, in New Zealand, Brazil and Romania.
The remaining four of Nathan’s list of minerals first identified in New Zealand are named after what they consist of. First, “hydrogrossular garnet” is a variation of the calcium-rich grossular garnet. The presence of water and thus hydroxide in its chemical make-up led to its name. The 1943 article in which Hutton announced its discovery can be found here. Interestingly, hydrogrossular garnet does not appear in the International Mineralogical Association’s official list of minerals. This was so unexpected to me that I checked it a number of times, even looking at previous versions of the official list. I could access the list going back to the 1960s but it did not appear even then. It took me a while to work out the reasons for its omission.
It turns out that, under the IMA’s rules, hydrogrossular is classified as a series name or variety name for a type of grossular garnet, rather than a unique mineral species. It needs to be noted at this point that minerals can often be described as solid solutions with varying compositions of some of their chemical constituents, rather than as substances with an exact chemical formula. There are often two “end-members” in a group or series of minerals – these are minerals at the extreme ends of the mineral series in terms of the purity of their chemical composition (Wikipedia). Hydrogrossular garnet is considered to lie between two officially recognised end-members of a garnet series, grossular garnet and katoite. As AlexStrekeisen puts it, “Hydrogrossular is a general term for OH-bearing garnet compositions from the grossular-dominant portion of the grossular-katoite series.” This does not mean that hydrogrossular does not exist as a mineral – rather its chemical composition is viewed as only a very minor variation of grossular garnet, failing to qualify as a separate mineral under IMA’s rules. A technical discussion of this can be found in a 2013 article in “American Mineralogist” titled “Nomenclature of the Garnet Supergroup”, see especially the “Hydrogarnets” section on page 790. Nevertheless, the term “hydrogrossular” is informally in common use in a consistent way, including in petrology, mineralogy and gemology, and does refer to a specific mineral composition closely related to grossular garnet.
“Feruvite” is a mineral that is part of the uvite group, and as it is rich in iron (iron’s symbol being Fe), it was named feruvite. It is a dark brownish-black iron-rich variety of tourmaline found in a coarse-grained granitic rock on Repanga/Cuvier Island which is located 23 kilometres south-east of Great Barrier Island. Philippa Black from the University of Auckland had noted the occurrence of an iron-rich tourmaline on Cuvier in 1971. She later provided specimens to Joel Grice and George Robinson of the National Museum of Natural Sciences, Ottawa, who found they contained this previously unknown mineral. Grice and Robinson published their discovery in 1989.
“Ferroceladonite” and “Ferroaluminoceladonite” were discovered in the 1990s when crystals from the Hokonui hills, east of Gore, were analysed by electron micro-probe. Previously the crystals had been identified as celadonite, a well-known mica group mineral found in altered volcanic rocks. However, the micro-probe analysis revealed two new minerals, their crystals being extremely small, only 1 to 2 microns thick. Ferroceladonite is clay-like, usually green, and includes fine coatings and powdery masses. It was named for its ferrous content and its relation to celadonite. Ferroaluminoceladonite is also reported to be usually green in colour though sometimes an off-white, is described as earthy, and its name reflects the significance of the presence of aluminium.
I have gone through the latest official list of minerals and have discovered two more New Zealand-origin ones that Simon Nathan didn’t note – a very old one, “taenite”, and a very new one, “waipouaite”. Taenite (see photo below left) is an alloy of iron and nickel found naturally on Earth but mainly in iron meteorites. It is opaque with a metallic greyish to white colour. Its name is derived from the Greek word for “band” as it sometimes is found in meteorites in bands interleaving with another mineral. It was originally described in an 1861 German-language article by Carl von Reichenbach (photo below), a German chemist, geologist, metallurgist, and industrialist with an interest in iron, magnetism, and meteorites, among many other things. The type locality for taenite is recorded as Gorge River in Westland. Von Reichenbach had contacts with Austrian geologist Ferdinand von Hochstetter, who conducted the first systematic geological surveys of New Zealand in 1858–1859 – that may have been the source of his taenite samples.
Waipouaite (above right) is a rare mineral noted in 2020 but not officially described until 2024, notable as the first natural “polyoxovanado silicate” ever discovered. It forms as tiny glassy dark olive-green to nearly black prismatic crystals. It was found in Aranga Quarry (also known as Stone’s Quarry or Hood Road Quarry) in Aranga in the Kaipara District, and is named after the local Waipoua Basalt formation which provides its host rock. Because of their unique and highly complex molecular architectures with industrial applications, synthetic polyoxovanadates have been heavily researched. Now waipouaite has proved for the first time that these molecular architectures can naturally form under specific geological conditions. I don’t understand any of the details of such matters, but it’s interesting to know that New Zealand geology has provided something like this.
The next Article in this Series is not yet available. The Series Index is here.
