Mineralogica

Tasmanica

The Official Journal and Newsletter of Mineralogical Society of Tasmania Inc.

Number 102 February 2019

Special Features in this edition. …… • President’s Report • Martian Soils in Scotland? • Publications • WA Seminar • Data-driven discovery reveals Earth's missing minerals • Carbon Mineral Challenge • Nataliyamalikite • Opal in Tasmania ?? • Seafloor Crocoite? • Chapman Collection

Lord Brassey Mine, Heazlewood District, Tasmania Bright green zaratite, in a halo after hellyerite, on greenish serpentine matrix.

Committee administrating the Mineralogical Society of Tasmania Inc.

Patron: Professor Ross Large, OA, President of the Royal Society of Tasmania President: Ralph Bottrill Email: [email protected] H. (03) 6267 1014, Mob 0429 173 055 Vice-Presidents: Colin Steedman, Tony Joyce Treasurer/Secretary/Public Officer Marnie Pope Email: [email protected] H. (03) 62442023 Field Trips Officer: Mathew Latham email: [email protected] Librarian: Brett Chandler email: [email protected] Newsletter Editor: Peter Manchester Email: [email protected] TLMA Delegates: Ralph Bottrill, Brett Chandler, Neil Newman ( TLMA President) Membership fees: $20: single, $30: family (includes 4 newsletters/yr) due at the time of the AGM. All correspondence to: P.O. Box 1111, Rosny Park, Tas., 7018 The general website about the Society: http://www.mineral.org.au/socs/taspg001.html

Guest speakers are frequently featured, and a “Short Talk” session enables members to become better acquainted with various mineral species and unusual minerals. Members often bring along minerals for sale, viewing and identification. Field trips are held most months, often in association with other clubs, with the venue being published in our newsletter.

Yellow-green witherite on kutnohorite, 60mm across 37 level Y lens, Rosebery. Found recently; Mathew Latham Collection.

MST 102 2 Program/ Events for Min. Soc. members

March 1st Meeting Dehne McLaughlin - Ramblings in Tucson 2019 March 16th & 17th Hobart Gem, Mineral & Fossil Show April 5th Meeting Dr Wei Hong - UTAS. "Heemskirk Tourmaline" May TBA? May 25th Trip Bridgewater June Meeting: Dr Angela Escolme: Utas: Mines of Sth America? July: TBA? August: AGM: R Bottrill: Microscopes? September TBA? October Bill Baker: Pyromorphite group November Tony Joyce TBA December: no meeting?

PRESIDENT'S REPORT … Ralph Bottrill Senior Geologist, Mineralogist and Petrologist, Metallic Minerals & Geochemistry, Mineral Resources Tasmania.

Happy New Year to all members!

After having our usual Christmas break, there are not too many recent events to report. Our February meeting was entertained by Steve Sorrell, visiting from Ballarat, and lecturing us on methods of Mineral Photography. Peter Manchester gave an interesting short talk on the hardest mineral on Earth.

In March Dehne gave a great talk on the Tucson mineral show, making us wish we could all be there!

We are progressing with an interesting program for the year, so please keep in touch.

“Chrome Cerussite”; Dundas, Tasmania, Australia

A variety of Cerussite. Not properly diagnosed yet. Claimed to be a mixture of Cerussite and Crocoite in Hey's Chemical Index of Minerals. More likely cerussite coloured by very small traces of Cr. MST 102 3

FIELD TRIP ROSTER FOR 2019

DATE LOCATION Club TRIP LEADER CONTACT Material

Hobart Showgrounds 62491408 or MAR 16-17th (Glenorchy) LCT Show RAST LCT R. Aheimer 0438 803 651

APRIL 7th CALDER Agate BDGC G. Turner 0490 100 053 0413 685 466 APRIL 14th MILTON* Petrified wood/Agate LCT Y. Briers $2 Per person **FLOWERY MAY 5th GULLY** Calcite MST R. Bottrill 0429 173 055

JUNE 15th

JULY 14th Lune River Petrified fern/wood LCT D. Ford 0409 773 027 0413 685 466 AUG 11th MILTON* Petrified wood/Agate LCT Y. Briers $2 Per person SEP TBA

OCT 12or13th Location TBA MST R. Bottrill 0429 173 055 -West Coast Heritage NOV 9th-10th Zeehan Gem & Mineral Fair Centre

LAUNCESTON GEM NOV 16-17th & MINERAL FAIR Location TBA N. Newman 0408 313 494 Petrified Fern / NOV 24th LUNE RIVER Wood LCT D. Ford 0409 773 027 DEC 1st CALDER Agates BDGC G. Turner 0490 100 053

DEC 15th TBA TBA NETLC V. Teichmann 0403 024 499

** SAFETY GEAR MUST BE WORN

* Fee per person required for Milton Trips.

PLEASE NOTE: CONTACT MUST BE MADE WITH THE FIELD TRIP LEADER AT LEAST 2 DAYS PRIOR TO A TRIP. SAFETY GEAR MUST BE WORN – WHERE REQUIRED. ADHERANCE TO THE CODE OF ETHICS IS EXPECTED AT ALL TIMES. TRIP LEADERS HAVE A RIGHT TO DECLINE ATTENDANCE IF SAID PERSON/S ARE NOT MEMBERS OF A TLMA AFFILIATED CLUB, OR IF SAID PERSON/S DO NOT ADHERE TO THE CODE OF CONDUCT.

MST 102 4 Publications endorsed by the Mineralogical Society of Tasmania. The Society has many publications associated with mineralogy sent to either the President or Secretary. These are available to members for reading… research etc. The Librarian keeps them in safe keeping for members. He often brings them along to meetings for members to borrow. Please ask to borrow them.

The Australian Journal of Mineralogy After a long absence, the AJM has been revitalized under new editorial management in West Australia. Details of new issues will be made available as soon as they come to hand.

If you want to know what's happening in minerals in Australia, the best place to find out is the Australian Journal of Mineralogy. It contains a wealth of material, published on high quality stock with numerous colour photos.

AUSTRALIAN JOURNAL OF MINERALOGY (AJM) team have released the latest issue (Vol 19, No. 1) continuing the high quality of previous issues. All Members should consider subscribing (if not already doing so!) and support your national mineralogical journal. Subscription details and news about the Journal can be found on their web-page and facebook-page: http://www.mineral.org.au/pubs/ajm.html https://www.facebook.com/AJMPublications/

Subscription (two issues): A$32.00 for two issues includes GST & Postage (rate within Australia)

Subscriptions may now be ordered from the new AJM secretary: Geert Buters [email protected] The AJM has also set up a Facebook page where the latest information will be posted as it comes to hand. www.facebook.com/AJMPublications Back issues are available – see Ralph Bottrill

The Monthly Mineral Chronicles is a publication pulled together by a mineral collector(Steve Sorrell) for mineral collectors. Each month, averaging around 80 pages with high quality colour photography, I publish mineral-related content from around the world.

There is a range of topics including mineral news and information, show reports, articles on minerals and localities, a spotlight on individual mineral dealers or collectors, and maybe an editorial now and again. So far there have been seven issues, plus one additional publication, a Collector's Guide to the Minerals of Flinders, Victoria. A second locality-specific publication is underway, a Collector's Guide to the Minerals of Spring Creek, South Australia.

The next issue of the Monthly Mineral Chronicles, out mid-March, will be all about this year's Tucson Show experience.

MST 102 5 All of this, and more, is available from US $1 per month. You can find out more here - https://www.patreon.com/join/CrocoArt

Minerals of the Kara Mine Steve Sorrell and Ralph Bottrill

Available from Lulu.com

MST 102 6 42th Joint Mineralogical Societies of Australasia – WA seminar update

Planning for the 42nd Seminar Traps in mineralogy – pseudomorphs, look-alikes, fakes and synthetics to be held in Perth in 2019 is well underway.

Events confirmed include: EVENT Date Venue Cost Micromount session Friday 30 August WA Lapidary Club –Rivervale $5.00/table Own lunch Welcome to Perth Friday 30 August – evening Crystal Universe - Subiaco Sponsored Seminar Day 1 Saturday 31 august State Library, Perth Cultural Centre See below Conference dinner –with auction (Donations for auction are welcome) Saturday 31 August TBC Around $60 Seminar Day 2 Sunday 1 September State Library, Perth Cultural Centre See below Evening function Sunday 1 September MinSocWA Patron Mark Creasy venue Sponsored Swap and Sell Monday 2 September WA Lapidary Club – Rivervale $5.00/table Gold coin for tea/coffee. Lunch sponsored (Allan Hart) Field trip Tuesday 3 September start Length around 7-10 days. Murchison Mineral Field Negotiations in progress with tenement holders. Self-drive, with some accommodation provided. Details and itinerary TBC; may require entry payments to some sites.

Costs to attend the seminar: Early bird – closes 28 February 2019 $135 MinSoc members (and like-societies) $150 Non-members $185 Students $75 Registrations via TryBooking will open in late November on our website http://minsocwa.org.au/ Registration costs (but not conference dinner) will be waived for speakers – email [email protected] if you are interested in presenting a talk related to the seminar topic. A mineral photo competition is being coordinated by John Mill, with 3 main categories: • Category 1 – subject less than 5 mm • Category 2 – subject between 5 and 30 mm • Category 3 – subject greater than 30 mm Digital entries to be submitted by 30 June 2019. Detailed guidelines are being finalized and will be posted on the website http://minsocwa.org.au/.

MST 102 7 Martian Soils in Scotland?

(Submitted by Dave Duncan).

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Data-driven discovery reveals Earth's missing minerals by Timothy Oleson Tim is the news editor at EARTH, and writes the Bare Earth Elements blog. His scientific interests span the geosciences from biogeochemistry to seismology to space science.

Fuelled by advances in computing power and analytical methods, researchers in a growing number of scientific fields have taken to mining large datasets to reveal big-picture insights.

Like biologists searching for undiscovered species, mineralogists have long sought to fill in the picture of Earth’s mineralogical diversity with new finds. In recent years, mineralogists, teamed with mathematicians and others, have begun using statistical models and data science methods traditionally applied to study large datasets in fields like linguistics, evolutionary biology and social network analysis. The researchers hope to reveal previously unseen patterns and clues hidden in mineralogical databases about Earth’s mineral diversity, and find undiscovered minerals — an effort that could enlighten our basic understanding of how our planet formed and has changed over billions of years, offer insights about the locations and largest of deposits of critical natural resources, and even unearth information about the histories of other rocky planets.

MST 102 9 Waiting to Be Found Among the more than 5,300 recognized mineral species are common rock-forming minerals, such as quartz (top left) and orthoclase (top right). Others, such as the colourful, copper-bearing minerals kröhnkite (middle left) and malachite (middle right), are less common but still known from many localities.

Most minerals, however, are documented based on just a few known occurrences. Petterdite (pink mineral at bottom left, seen with yellow cerussite) has been reported from just two locations, according to Mindat. while martinite (bottom right) has only been reported from a single site.

Credit: Clockwise from top left: Didier Descouens, CC BY-SA 4.0; Didier Descouens, CC BY-SA 4.0; ondra244, public domain; Modris Baum, public domain; Ralph Bottrill, CC BY 3.0; Ra’ike, CC BY-SA 3.0

The International Mineralogical Association (IMA) currently recognizes 5,327 distinct mineral species. Some, such as the major rock-forming silicates and carbonates, are well known and found in abundance the world over. But most are documented based on just a few known occurrences. It’s unlikely that scientists will stumble across many new finds of singularly abundant minerals on Earth, but numerous rare minerals are yet to be discovered.

Missing Minerals and How to Count Them Considering how long mineral hounds, professional and amateur alike, have been scouring Earth’s surface, it might be hard to imagine there could be many minerals left to find. But there is no shortage of potential mineral compositions or structures, as demonstrated by the vast range of crystalline compounds that have been created synthetically. And there are plenty of reasons why mineral species might have been previously overlooked.

For example, mineral hunters have historically been drawn to big, colourful, valuable or otherwise remarkable specimens. But many minerals do not fit any of those criteria. Additionally, some minerals are only stable under a narrow range of pressure and temperature conditions, or they aren’t stable under the conditions near Earth’s surface. Bridgmanite, for example, is perhaps the most abundant mineral on the planet, constituting the bulk of the lower mantle, but it is essentially absent from Earth’s surface, and was only formally recognized in 2014. MST 102 10

Several years ago, Hazen and his colleagues realized that the large amount of existing information in databases, such as the University of Arizona-based RRUFF Project and the Mindat website, which collects both literature- and crowd-sourced information, could offer clues about the number, nature and whereabouts of these unknown minerals.

In 2014, Hazen, along with mathematician Grethe Hystad of Purdue University Northwest and others, began analyzing the hundreds of thousands of mineral-locality pairings collected in Mindat. Each report of a given mineral at a specific location in Mindat represented a single datum, and collectively, the dataset provided a “frequency spectrum” of Earth’s known minerals, charting the number of different species known from only one site on the planet, followed by the number known from two sites, three sites, and so on. The plot highlighted the striking disparity between the large number of rare minerals compared to the relative few found at many locations.

In a 2015 a study published in Mathematical Geosciences, Hystad, Hazen and Robert Downs of the University of Arizona applied LNRE modelling to the mineral-locality dataset from Mindat. After fitting the data to LNRE functions, they estimated that Earth’s total inventory of minerals should number at least 6,394 — or 1,563 more than the 4,831 that were recognized at the time. It was, Hystad notes, the first quantitative prediction of Earth’s total mineral inventory using such a technique.

“The way we discover minerals keeps changing,” Hazen says. Early mineral finds were made by identifying them in hand samples or under light microscopes. More recent discoveries have required researchers “to use X-ray diffraction or an electron microprobe or a transmission electron microscope — as you get more and more sophisticated techniques, many more minerals become accessible,” he says, even if fewer people have the means to find them.

Abellaite (left) and parisite-(La) (right), both rare carbonate minerals, are two of more than a dozen carbon-bearing minerals newly recognized in the last couple of years. Credit: left: Matteo Chinellato, CC BY-SA 4.0; right: courtesy of Shaunna Morrison.

MST 102 11 Announcing the discovery of a new mineral: Nataliyamalikite Story Source: Materials provided by Monash University. Note: Content may have been edited for style and length.

In the harshest of environments in far-east Russia, Monash scientists have played a leading role in the discovery of a new mineral, which could revolutionise the future of the mining industry.

The mineral -- Nataliyamalikite -- is new, explains Professor Joël Brugger, the lead author in a recently published paper in American Mineralogist.

It contains thallium, a rare heavy metal most famous for its qualities as a poison.

"The discovery of this new mineral means we will be able to better understand how metals are extracted from deep-seated sources within our planet, and concentrated at shallow levels to form economic ore deposits," Joel said. "This will give us a unique insight into the processes responsible for the geochemical evolution of our planet. And this understanding is required to sustain mining -- a key to Australia's ongoing economic prosperity," Professor Brugger said.

A significant part of the recently published paper is about the formal description and naming of the new mineral (a process overseen by the International Mineralogical Association).

"Our Russian colleague was the first to see the mineral under the electron microscope," Professor Brugger said. "However, Monash was key to making the naming of the new mineral possible: we combined state-of-the-art sample preparation at our Monash Centre for Electronic Microscopy facility, along with the unique capabilities of the Australian Synchrotron, to obtain the of the mineral. "Understanding the crystal structure is akin to getting the full genome of the new mineral," Professor Brugger said. And in the case of Nataliyamalikite this was incredibly difficult as the grains are tiny and almost invisible."

The new mineral was discovered in the Kamchatka Peninsula -- one of the most active volcanic zones in the world, featuring 160 volcanoes including 29 that are active.

According to Professor Brugger, who spent six weeks in the region, it is also one of the few remaining wild oases on this planet, a result of politics (off-limit for a long time due to its military significance for the Soviets) as well as geographical isolation (no road connection to mainland Russia) and harsh climate.

Around 150 new minerals are discovered around the world every year, and the recently published article by Professor Brugger marks the official birth of one of them.

Read Professor Brugger's article at: http://www.minsocam.org/msa/Ammin/AM_Preprints/6057BruggerPrepringAug.pdf

MST 102 12 The Carbon Mineral Challenge The Carbon Mineral Challenge sets the stage for both professional and amateur mineral collectors to make their mark by discovering never-before described minerals. Researchers predict at least 135 of Earth's carbonbearing minerals remain undiscovered. Below are some recent discoveries

1. Close up of the new minerals: merelaniite The tiny, silvery, cylindrical whiskers are a new mineral—merelaniite— named for a mining region in Tanzania. Credit: Michigan Tech, John Jaszczak.

2. Abellaite Date December 2015 NaPb2(CO3)2(OH), A predicted carbon mineral Location Eureka mine, Catalonia, Spain, Structure Hexagonal Ref. MINDAT

3. Tinnunculite Date January 2016 Location Mt. Rasvumchorr, Kola peninsula, Russia Chemistry C5H4N4O3·2H2O Structure Monoclinic: P21/c Ref. MINDAT.

4. Marklite Date February 2016 Location Friedrich-Christian mine, Baden-Würtenberg, Germany Chemistry Cu5(CO3)2(OH)6·6H2O Structure New structure type Monoclinic: P21/c; Ref. MINDAT.

5. Middlebackite Date April 2016 Location Iron Monarch quarry, South Australia, Australia Chemistry Cu2C2O4(OH)2 Structure New structure type, Monoclinic: P21/c; structure determined Ref. MINDAT. The manager of the Iron Monarch quarry discovered the mineral Middlebackite. It was named for the quarry’s home, the Middleback Range in Australia, where another 163 minerals have been identified, 17 of them containing carbon. The Middlebackite sample was discovered in 1990, but only characterized as a new mineral species some 25 years later when sophisticated analytical tools made it possible to identify the structure of this new carbon mineral. Type material is deposited in the mineralogical collections of the South Australian Museum, Adelaide, Australia, registration number G34300.

MST 102 13 6. Leószilárdite Date June 2016 Location Markey Mine, Utah, USA. Chemistry Na6Mg(UO2)2(CO3)6·6H2O Structure New structure type, Monoclinic: C2/m; Refer. MINDAT. Leószilárdite, a rare, ephemeral, and -soluble uranyl carbonate mineral, was a particularly exciting discovery. Uranyl minerals are radioactive and have distinctly vibrant colours with many species brightly fluorescing under ultraviolet light. In groundwater, uranium is often carried alongside carbonate, with the potential for uranium to be transported for long distances. Named in honour of Leó Szilárd, Hungarian-born physicist and inventor (1898–1964). It was found in a single area of the Markey Mine, on a seam of Crich material deposited by an ancient stream. After mining ceased, groundwater ate away at the uraninite ore within this seam and produced abundant U-carbonate secondaries like andersonite, bayleyite, and čejkaite, with very minor leószilárdite. There was only a single specimen with diffraction worthy crystals from that trip (shown in the picture), since the bulk of the mineral occurs as pearlescent masses very thin plates. Type material is deposited in the mineralogical collections of the Natural History Museum of Los Angeles County.

7. Triazolite

Date August 2017 Location Pabellón de Pica, Chanabaya, , Chile Chemistry NaCu2(N3C2H2)2(NH3)2Cl3·4H2O Structure Orthorhombic, Refer. MINDAT. Guano deposits are the source of several recently discovered new minerals. A bird, the guanay cormorant, is the most likely source of the guano that produced the newly discovered–and exquisitely beautiful–mineral triazolite. Crystals of triazolite overgrow surfaces of hard rock (gabbro) or occur in cavities in aggregates of salammoniac, a rare mineral composed of Chloride. Triazolite is chemically and structurally related to chanabayaite, for which it is a precursor phase. Mineral collectors first found triazolite in the Tarapacá region of Chile. Type material is deposited in the collections of the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow, Russia, registration number 5037/1 Triazolite locality in Chile, credit N. Chukanov. This photo depicts the guano deposit situated at Pabellón de Pica, Chile. Chukanov believes that Guanay cormorant (Phalacrocorax bougainvillei) was the most important producer of Chilean guano.

MST 102 14 8. Ramazzoite Date December 2017 Location Monte Ramazzo mine, Genova, Liguria, Chemistry Mg8Cu12(PO4)(CO3)4(OH)24(H2O)20][(H0.33SO4)3(H2O)36 Refer. MINDAT, European Journal of Mineralogy. Ramazzoite is the first mineral found in nature that contains a polyoxometalate cation, or positively charged ion. Polyoxometalate ions are made up of clusters of metal atoms bound together by oxygen atoms. While scientists have produced many compounds with polyoxometalate anions (negatively charged ions) in the laboratory, polyoxometalate cations are extremely rare. Another unique feature of ramazzoite is that it has a large variety of anions. Typically, a mineral has just one or two types of anion, but ramazzoite contains four–phosphate, carbonate, hydroxide, and sulfate–making ramazzoite a truly extraordinary find.

9. Edscottite Fe5C2 Date January 2019 ( no photo)

Sample from Wedderburn meteorite, found 4.5 km NE of Wedderburn, Victoria, Australia (36°26′S, 143°38′E). Type material is deposited in the meteorite collections of the Department of Earth, Planetary and Space Sciences, University of California, Los Angeles, CA 90095-1567, USA, polished thick section ULCA 143.

10. Paddlewheelite Date January 2018 Location Svornost Mine, Bohemia, Czech Republic Chemistry MgCa5Cu2(UO2)4(CO3)12(H2O)33 Structure Monoclinic . Refer. MINDAT. Paddlewheelite is one of the rarest carbonate minerals found in the Svornost mine in the Czech Republic, and among the rarest of all known carbonate minerals. Paddlewheelite has a unique structure suggesting the paddle wheel of an old-fashioned steamboat. Uranyl carbonate clusters form the wheel, which is held together by axles made of copper and with a gearbox made of calcium atoms.

11. Davidbrownite-(NH4) Date December 2018 Location: 125 foot level, Rowley Mine, Theba, Painted Rock District, Painted Rock Mts, Maricopa Co., Arizona, USA

4+ Chemistry (NH4)5(V O)2(C2O4)[PO2.75(OH)1.25]4·3H2O : Monoclinic Davidbrownite. The deep blue crystals in the image are antipinite. Photograph by Anthony Kampf.

MST 102 15 12. Carmeltazite, Date 08 January 2019 An article published in the journal Minerals in December detailed the makeup of carmeltazite, named for Mount Carmel in northern Israel. The mineral contains titanium, aluminium and zirconium, and its formula is ZrAl2Ti4O11. It is found within a type of sapphire on the project site. Shefa Yamim CEO Avi Taub said the ID was exciting for the company. "We are delighted that our Carmel sapphire has been recognized as a host to many rare minerals. In today's world where the prices of gems are determined predominantly by their rarity, the Carmel sapphire is a unique discovery." The research published by a group led by geologist Bill Griffin at Macquarie University in Australia, and included researchers from the University of Western Australia, Università degli Studi di Firenze and Università degli Studi di Milano. Shefa Yamim has done a bulk sampling programme at Mount Carmel, and says it has found diamonds, sapphires and rubies. …… (Jan 15, 2019 Helen Flatley)

Crystalline gold, Back Ck. Found recently by Ron Gregory; Mathew Latham Collection. Gold is 10x10x7mm 3.09g.

MST 102 16 Why don’t we have OPAL deposits like on the mainland in Tasmania ? A question asked of the editor recently on a geo tour trip? Opal is Australia's national gemstone but no new significant opal fields have been made since the early 1900s.

Most opal exploration is carried out by individual miners digging in desolate areas around old opal fields in the Great Artesian Basin.

"Unlike in gold exploration, there are no accepted concepts or methodologies available to guide opal miners where new fields may be found, and there are as many theories as there are opal miners," said Dr Adriana Dutkiewicz, part of the opal research team from the University's School of Geosciences.

A Google Earth map showing the regions prospective for opal (light) vs non-prospective regions (dark) based on data mining, with magenta dots outlining existing opal mines. These conditions involved alternating shallow seas and river systems followed by uplift and erosion.

The environmental changes occurred from about 145 million years ago (during the Age of the Dinosaurs) until the present-day and shaped the surface of vast parts of outback Australia.

Most Australian precious opal is found near the rim of the Great Artesian Basin

MST 102 17 Seafloor Crocoite? Ralph Bottrill and Dr Rebecca Carey (UTAS)

On behalf of the NESP Marine Biodiversity Hub, Rebecca is assisting the Seamount Corals Survey taking place on the CSIRO RV Investigator, south of Tasmania. The deep tow camera being operated from the ship has spotted areas of what some scientists (generally not geologists) thought it was crocoite and sent photos to Ralph who says it might be a red zeolite like Thomsonite (or something organic?).

We are running a daily blog about the voyage, and may do a story: See Bethany Green’s blog on https://www.nespmarine.edu.au/seamounts/landing-page. (I spoke to Rebecca the other day and they got a seafloor sample from the area, but no red crystals sadly).

Red crocoite-like material from the basaltic Mongrel seamount in the Southern Ocean.

Two Tasmanian diamonds, from near Savage River. Tasmanian Museum and Art Gallery collection. Both about 3mm diameter. R Bottrill photos.

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