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DISPLAYING POSTS TAGGED: dynamic earth (6)

Banded iron slab

Author
by Kate C
Publish date
11 June 2013
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Early this morning, we installed a huge, beautifully polished slab of banded iron at the entrance of the Dynamic Earth exhibition at Melbourne Museum.

Banded iron slab The banded iron slab showing its gorgeous coloured layers.
Source: Museum Victoria
 

The slab, donated by stonemason and artist Richard Williamson, is about three metres high and weighs 870 kilograms. Its wavy bands of red jasper and brown iron oxides record the rise of oxygen in the Earth's atmosphere.

About 2.7 billion years ago, the first oxygen-producing cyanobacteria (blue-green algae) completely transformed the Earth by releasing oxygen during photosynthesis. Over hundreds of millions of years, this oxygen reacted with the iron that was dissolved in the ocean, forming solid iron oxides and silica which settled on the ocean floor. It was only once all the iron precipitated out of the oceans that oxygen began to build in the atmosphere, and the Earth became habitable for multicellular life forms like us. There is, however, approximately 20 times more oxygen within the banded iron formations than is present in the atmosphere today.

  Banded iron slab installation The slab resting on its A-frame and about to be positioned with the slab lifter.
Image: Heath Warwick
Source: Museum Victoria
 

This piece of banded iron formed about 2.5 billion years ago in the area that is now the Pilbara in Western Australia. It was subsequently buried and metamorphosed, or transformed under extreme pressure, changing the minerals and creating the folds and waves of its layers. Among the red bands of fine-grained silica called jasper, and black layers of iron oxide, you can see shimmery yellow lines of tiger-eye, a fine-grained quartz that has replaced a fibrous mineral.

team installing rock slab Ant, Nev and Veegan using the folklift to lift the 870kg slab and guiding it into its support brackets.
Image: Heath Warwick
Source: Museum Victoria
 

Banded iron is the major source of the world's iron ore. Most of these large iron ore deposits formed between 2.5 and 1.8 billion years ago. It is mined and fed into blast furnaces to extract the metal. This piece escaped that fate because of its unusual beauty and size; it is rare to find such a large piece that has no veins of quartz, which often cause fractures. The rock, once a huge boulder, was extracted from the Ord Ridley Ranges, cut in Perth and polished in Adelaide.

installing the rock slab View through the dinosaurs of the slab in its new home.
Image: Heath Warwick
Source: Museum Victoria
 

Installing such a huge specimen was quite a feat. In the wall behind the rock, steel supports and counterweights hold it securely in place. Bringing it into the gallery took a team of people and a forklift designed to lift and move concrete slabs for building construction. The crew brought the slab in on an A-frame trolley, lifted it, and inched it carefully into its specially-designed support brackets.

And yes, you can touch it!

Dermot with the banded iron slab Manager of Natural Science Collections Dermot Henry next to the newly-installed slab of banded iron.
Image: Heath Warwick
Source: Museum Victoria
 

Lava on location

Author
by J. Patrick Greene
Publish date
3 January 2013
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Comments (1)

While on holiday recently, I visited Big Island in Hawai'i to see the active volcanoes and lava flows. My interest was sparked by the exhibit in the Dynamic Earth exhibition at Melbourne Museum which includes a large sample of 'ropy lava' that visitors are invited to touch. The name describes the ribbed appearance of the lava that looks like a collection of ropes formed as the liquid lava cooled. The Hawaiian name for this form of lava is pahoehoe.

Ropy lava Ropy lava, or pahoehoe, from Hawai'i's Kilauea volcano.
Image: Patrick Greene
Source: Patrick Greene
 

I visited the Kilauea volcano which is currently active. In the vast caldera is a crater holding a lava lake. Great quantities of volcanic gases rise from the lava lake and the orange glow from the molten lava is visible. It would be very dangerous to stand downwind of the vog (volcanic fog) as it contains large quantities of sulphur dioxide and other noxious gases.

Volcanic fog rising from lava lake Volcanic gases rising from Kilauea's lava lake.
Image: Patrick Greene
Source: Patrick Greene
 

Around the caldera are steam vents, where lava flowing through underground tubes heats rainwater seeping though the ground and turns it into steam. Visitors can walk through a large extinct lava tube.

I explored three lava flows that originated in the Mauna Ulu vent on the flank of Kilauea. It is essential to wear sturdy footwear and the tread very carefully, for a fall onto the abrasive, glassy surface can result in serious injury. Each flow was different in character as the mix of lava and gases and form of each eruption varies. The third lava field that I visited produced the most impressive ropey lava, with a smooth shiny surface that glistened in the sunlight. The stream of viscous lava had hardened where it had cooled leaving vivid evidence of the way in which it had flowed from the Mauna Ulu vent. It was fascinating to walk to the edge of the flow to see where the lava had stopped, leaving the trees and other vegetation untouched. Also interesting to see were plants that had managed to gain a foothold on the lava as recolonisation is taking place thirty or forty years after the eruption.

Plants slowly recolonising lava fields. Plants slowly recolonising lava fields.
Image: Patrick Greene
Source: Patrick Greene
 

I was unable, on this occasion, to visit the active lava flows from another of Kilauea's vents that are flowing into the sea, constantly enlarging Big Island. That's a prospect for another visit!

Links:

Photos: Kilauea Lava Reaches the Sea via National Geographic

Coloured diamonds

Author
by Nicole K
Publish date
19 August 2012
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Comments (1)

Your Question: How do diamonds get their colours? What's so special about the pink ones?

Diamonds are made up of carbon atoms arranged in rigid tetrahedrons (triangular pyramids).  Pure diamonds are transparent and colourless. They are very rare and therefore very valuable.

Five diamonds from E.J Dunn collection found in Beechworth Five diamonds from E.J Dunn collection found in Beechworth.
Image: Frank Coffa
Source: Museum Victoria
 

Most naturally-coloured diamonds are created when trace elements interact with the carbon atoms during the diamond's creation. The presence of chemical elements such as nitrogen, sulphur, and boron can colour diamonds in shades of yellow, green and blue.

Diamond specimens from the Great Southern mine (Rutherglen, Victoria). Diamond specimens from the Great Southern mine (Rutherglen, Victoria).
Image: Frank Coffa
Source: Museum Victoria
 

Pink diamonds, however, are a different story.Trace elements have never been found in pink diamonds. Instead, the colour is caused by a distortion in the diamond's crystal lattice, created by intense heat and great pressure from all directions (non-isotropic stress) after the stone's formation in the earth. This distortion displaces many carbon atoms from their normal positions and alters the qualities of light reflected by the diamond. It is this special configuration of the molecules that allows us to observe the stone as pink.

Although pink diamonds are found throughout the world, pink diamonds from the Argyle Mine are said to have the finest colour of fancy, intense pink (colour saturation). This is because Argyle pinks possess densely-packed graining planes that emanate pink colour (twinning lamination). In contrast, non-Argyle pinks have few and indistinct pink graining and are therefore generally lighter in colour. The pink graining in Argyle stones is sometimes visible to the naked eye.

Pink diamonds are not just special because of their structure; they're also incredibly rare: for every one million carats of diamond produced at Argyle, only one carat will be of high-quality pink colour.

The Argyle Pink Jubilee diamond (from Argyle Diamond Mine, WA): the largest pink diamond ever found in Australia, donated to Museum Victoria by Rio Tinto. The Argyle Pink Jubilee diamond (from Argyle Diamond Mine, WA): the largest pink diamond ever found in Australia, donated to Museum Victoria by Rio Tinto.
Image: John Broomfield
Source: Museum Victoria
 

The largest pink diamond ever found in Australia is the Argyle Pink Jubilee diamond (8.01 carats). It was donated to Museum Victoria by Rio Tinto and is currently on display in Melbourne Museum's Dynamic Earth exhibition.

Got a question? Ask us!

Links:

Museum Victoria: Australia’s largest pink diamond

Melbourne Museum: Dynamic Earth

Museum Victoria: Diamonds

The Age: Rare diamond puts Melbourne Museum in the pink

Moon rock now on display

Author
by Ursula
Publish date
19 June 2012
Comments
Comments (6)

Ursula Smith works in the natural sciences collections at Museum Victoria. Though a palaeontologist by training she finds all the collections fascinating and swings between excitement at all the cool stuff in them and despair at the lack of time to look at it all.

Museums make it possible to see specimens from faraway places that you won't get the chance to visit yourself. And it doesn't get much further away than the Moon – a piece of which we've received on long-term loan from NASA for display in Dynamic Earth. It was installed just this morning.

Moon rock Moon rock in its protective glass case, now on display in Dynamic Earth. Behind it is the exhibition's Moon model.
Source: Museum Victoria
 

It's a small piece cut from a larger rock, lunar rock 15555, dubbed 'The Great Scott' after Commander David Scott who collected it during the Apollo 15 Lunar Mission in July 1971. Its specially-built glass case is filled with nitrogen to protect the rock from Earth's atmosphere.

Moon rock is incredibly rare - we have not quite 800kg in total on Earth, which is lighter than an average family car. It's also incredibly important because of what it can tell us about the Moon's formation.

The Great Scott is a basalt formed from a volcanic eruption. It's similar to basalts found on Earth, being composed of silicate minerals such as olivine, pyroxene and plagioclase, except that basalts from the Moon lack water.

Great Scott moon rock Apollo 15555, 'The Great Scott'. The dent in the centre of the visible surface is a "zap pit" - a hole caused by the impact of a micro-meteorite.
Source: NASA
 

The Great Scott is 3.3 billion years old and has been sitting on the surface of the Moon for 80 million years, since long before the dinosaurs went extinct! We can tell this by measuring how long its minerals have been exposed to cosmic radiation. The rock still looks amazingly fresh because the Moon has no atmosphere, meaning very little weathering has occurred.

Apollo 15 was the fourth of the Apollo missions to land on the Moon and the first to involve significant geological training for the crew. 

Three men in space suits The Apollo 15 Crew standing in front of the Lunar Rover: Cmd. David Scott, CMP Wolden, LMP Irwin.
Source: NASA
 

The landing site for Apollo 15, Mare Imbrium, was selected specifically to allow investigation of three different landscape features: a mare basin, a mountain front and a lunar rille. Mare Imbrium is so large that it's visible to the naked eye from Earth. It was hoped that Apollo 15 would be able to collect Pre-Imbrian material – rock exposed or thrown out by the impact that formed the enormous crater.

  The Moon showing Mare Imbrium. The Moon showing Mare Imbrium.
Source: Wikipedia
 

Another of the primary goals of the Apollo 15 mission was an examination of Hadley Rille, a channel-like depression in the lunar surface. During their three-day stay on the Moon, Scott and Irwin traversed over 28km in the lunar rover – the first time a vehicle had been driven on the Moon's surface.

At Hadley Rille they collected a large proportion of the rocks that were brought back to Earth, including Apollo 15555. Weighing 9.6kg on Earth, the rock weighed only 1.6kg on the Moon so it was easy to carry.

Moon rock in situ on the Moon Apollo 15555 prior to Commander Scott collecting it. The tripod structure is a gnomon used to indicate the direction and elevation of the sun.
Source: NASA (Image AS15-82-11164)
 

NASA distributed rock from the Apollo missions to researchers around the world for study, including Museum Victoria Honorary Associate Professor John Lovering. At the time of the Apollo program he was the Head of Earth Sciences at the University of Melbourne.

Professor Lovering carried out some of the very first chemical analyses of the Moon rock from Apollo 11 and 12, and discovered a new mineral, tranquillityite, which has since been found on Earth – from six localities in Pilbara, Western Australia – as well as from rocks from every Apollo mission and a lunar meteorite.

Man and vehicle on the Moon LMP Irwin and the Lunar Rover, taken by Cmd. Scott
Source: NASA (Image A515-86-11603)
 

Links:

Infosheet: The Moon

MV Blog: Distant Moon

Apollo Lunar Surface Journal

Lovering, J. F. et al (1971). Tranquillityite: A new silicate mineral from Apollo 11 and Apollo 12 basaltic rocks. Proceedings of the Lunar Science Conference 2: 39–45.

MV Blog: Murchison meteorite

Murchison meteorite

Author
by Ursula
Publish date
5 December 2011
Comments
Comments (5)

Ursula Smith works in the natural sciences collections at Museum Victoria. Though a palaeontologist by training she finds all the collections fascinating and swings between excitement at all the cool stuff in them and despair at the lack of time to look at it all.

I’ve been asking the people who work with MV collections what some of their favourite items are, starting with Dermot Henry, the Manager of the Natural Sciences Collections.

Dermot's speciality is geology and he’s looked after the geosciences collections for many years. When asked what his favourite item was he took care to tell me that he didn’t have a favourite because there are so many fascinating objects, but when pressed he picked the Murchison meteorite as "probably the most famous and scientifically important rock in the collections."

The Murchison meteorite is one of 16 meteorites known from Victoria, and is rare in that it was actually observed falling, rather than just being found on the ground, so it came to scientists fresh (other than some surface dirt from falling into mud and cowpats and the like). It exploded in the atmosphere over Murchison, Victoria, about 160km north of Melbourne, on 28 September, 1969 and fell over an area around 35km2. So when we talk about 'it' we’re really talking about lots of broken pieces of a single object.

  Geology exhibition display Display in Dynamic Earth.
Image: Ursula Smith
Source: Museum Victoria
 

These pieces are on display in Dynamic Earth and are just a very small portion of what was collected. The largest piece found weighed nearly 7kg though many more were just a few grams each. In total, around 100kg was collected and over 80kg of that made it into science collections. While a lot of the material went overseas (mostly to the Field Museum in Chicago who have nearly 52kg and the Smithsonian in Washington DC who have nearly 20kg) some remained in Australia. Over 7kg stayed at the University of Melbourne and much of this was later donated to Museum Victoria. We have about 3.5kg and only the largest pieces that are on display; we also have lots of smaller pieces.

Drawer containing pieces of Murchison meteorite Drawer containing pieces of Murchison meteorite.
Image: Ursula Smith
Source: Museum Victoria
 

Most of the pieces of rock in this drawer are parts of the Murchison meteorite (though not the big rock on the right – that’s actually a different meteorite of a similar type called Rainbow that was found in Victoria in 1994). Opening the sealed tubes, you can still smell, very faintly, what Dr. John Lovering from the University of Melbourne who organised the collection of the meteorite pieces in 1969 described as "just like methylated spirits – very strong". This was the first indication that the meteorite he was looking at was a rare type called a carbonaceous chondrite. Unlike more common rocky meteorites, a carbonaceous chondrite is packed full of organic molecules and a lot of water; this one is eight per cent water.

The year after it was collected, papers began to appear in scientific journals describing the chemical composition of the meteorite and excitement about its scientific significance began to grow. A paper in the journal Nature describing the discovery of amino acids of extra-terrestrial origin in the meteorite made, if you’ll pardon the pun, quite an impact, and was widely covered in the press, even making it into Time Magazine. Papers are still being published on it – one came out in August this year in the Proceedings of the National Academy of Sciences, and a new chromium sulfide mineral, Murchisite (Cr5S6), was just reported in American Mineralogist.

To date over 70 amino acids have been identified from the meteorite, only 19 of which are known from Earth. These, and the many other chemicals that have been identified, suggest there could be thousands of complex organic chemicals present. What’s so interesting about these molecules is that they demonstrate that the simple chemical building blocks necessary for life on Earth seem to form quite easily in other places.

It isn’t just the origins of life that the Murchison meteorite may tell us about. It contains tiny pre-solar grains – nano-diamonds and silicon carbides, among others, that formed in supernovas long before our own sun appeared – which tell us a lot about how our own, and other, solar systems formed. But not only that, information from the pre-solar grains in the Murchison meteorite has been fundamental in figuring out a lot about how elements are originally produced and a lot about the structure and mechanics of stars.

So the Murchison meteorite is definitely pretty cool – biologists, chemists, astrophysicists and those of us who just think rocks that fall out of the sky are fascinating all agree on that. As Dermot says, "it’s so unusual and it’s yielded so much information about cosmology, element formation and how the universe works – it’s probably generated more publications than any other meteorite. And it’s Victorian!"

Murchison meteorite pieces Two pieces of the Murchison meteorite in Dynamic Earth.
Image: Ursula Smith
Source: Museum Victoria
 

Links:

Infosheet: Meteorites

Video: The Murchison meteorite story

Dermot A. Henry, 'Star Dust Memories - a Brief History of the Murchison Carbonaceous Chondrite'. Publications of the Astronomical Society of Australia, 2003. 20: vii-ix (PDF, 1 MB)

Gem of a proposal

Author
by Kate C
Publish date
21 April 2011
Comments
Comments (5)

There are a lot of sparkling gems and minerals on display in Dynamic Earth but on Tuesday morning there was a new temporary exhibit with an unusually personal label...

Ring in exhibition showcase Engagement ring planted in an exhibition showcase in Dynamic Earth.
Image: Heath Warwick
Source: Museum Victoria
 

But who put it there? And why?

Simone sees the showcase. Simone sees the showcase.
Image: Heath Warwick
Source: Museum Victoria
 

It was all part of an elaborate surprise marriage proposal by David to Simone. She thought she was visiting the museum to take some promotional photographs. All seemed perfectly normal until she spotted the showcase containing an engagement ring and the label asking 'Simone, will you marry me?'

Congratulations David and Simone! It was a lot of fun for the museum to be in cahoots with the lucky groom-to-be.

The newly-engaged couple The newly-engaged couple, David and Simone.
Image: Heath Warwick
Source: Museum Victoria
 

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Updates on what's happening at Melbourne Museum, the Immigration Museum, Scienceworks, the Royal Exhibition Building, and beyond.

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