Canada’s Barrick Gold

Canada’s Barrick Gold (NYSE:ABX)(TSX:ABX) said Thursday it will suspend operations at its Lumwana copper mine in Zambia, after the country increased this week mining royalties from 6% to 20%.

The world’s largest gold producer said the new tax regime, expected to go into effect on Jan.1, left the company “no choice” but to initiate the process of halting operations at its open pit mine.

“Despite the progress we have made to reduce costs and improve efficiency at the mine, the economics of an operation such as Lumwana cannot support a 20% gross royalty, particularly in the current copper price environment," said Barrick’s co-President Kelvin Dushnisky.

Major job cuts at the mine, which employs about 4,000 people directly, are planned to begin in March

Major job cuts at the mine, which employs about 4,000 people directly, are planned to begin in March, following the legally required notice period for putting the mine in care and maintenance, Barrick said.

The Toronto-based company also revealed it expects to record an impairment charge related to Lumwana, acquired when it bought Equinox Minerals Ltd. in 2011, in the fourth quarter of this year.

All operations at Lumwana, located in Zambia's Northwestern Province, should be fully cancelled by the second quarter of 2015, Barrick added.

The Southern Africa nation is one of the world's key copper producers and Barrick's decision to shut Lumwana makes the miner the first to react to Zambia’s new royalty rates.

In the first nine months of this year, the mine produced 138 million pounds of copper at C3 fully allocated costs of $2.98 per pound. The mine had 6.6 billion pounds of copper in reserves as of December 31, 2013.

Barrick had warned in October that it would consider suspending the mine if the Zambian government didn’t change the proposed new tax system, as it would threaten the operation’s viability.

Lucapa Diamond

Shares of Australia-based Lucapa Diamond (ASX:LOM) gained almost 4% Thursday after the miner announced Thursday it will begin mining at its Lulo alluvial concession in Angola in January.

In a first phase the miner plans to target high-grade diamond ore bodies, meeting a target of 14,000 bank cubic metres (bcm) per month before the end of June.

In the second half of the year Lucapa will bring in additional earth moving machinery to ramp up production to about 40,000 bcm per month.

In the second half of the year Lucapa will bring in additional earth moving machinery to ramp up production to about 40,000 bcm per month.

The company’s new chief executive officer Stephen Wetherall noted that mining in Stage 1 would focus on select areas within the licence area, which produced higher grades during the bulk sampling programs.

Lulo, about 700 kilometers (435 miles) east of Angola’s capital Luanda, could be even more valuable than the country’s biggest gem producer, Catoca, which is also the world’s fourth-largest kimberlite mine, Lucapa managing director Miles Kennedy has said.

World's rarest gems

The project, a joint venture between the company and the Angolan government, hosts type-2a diamonds, which the company qualifies as "the world's rarest and most valuable gems". These kinds of precious rock account for less than 1% of global supply and, according to Lucapa, the world's most famous large, white, flawless diamonds belong to this category.

Angola is the world’s No.4 diamond producer by value and No.6 by volume. Its industry, which began a century ago under Portuguese colonial rule, is successfully emerging from a long period of difficulty as a result of a civil war that ended in 2002.

The government has recently reduced taxes and cut state ownership requirements as it seeks to rekindle the industry after the global financial crisis forced mines to close.

Earth is closest to the sun every year in early January

Tonight – that is, before dawn tomorrow from our North American longitudes – our planet Earth will reach perihelion, its closest point to the sun for the year. This annual event will take place on January 4, 2015 at 6:36 UTC (01:36 a.m. EST). The word perihelion is from Greek roots peri meaning near, and helios meaning sun.

Earth is closest to the sun every year in early January, when it’s winter for the Northern Hemisphere. We’re farthest away from the sun in early July, during our Northern Hemisphere summer.

Earth is about 5 million kilometers – or 3 million miles – closer to the sun in early January than it will be in early July. That’s not a huge change in distance. It’s not enough of a change to cause the seasons on Earth.

Despite what many may think, Earth’s distance from the sun isn’t what causes the seasons. On Earth, because our orbit is so close to being circular, it’s mostly the tilt of our world’s axis that creates winter and summer. In winter, your part of Earth is tilted away from the sun. In summer, your part of Earth is tilted toward the sun. The day of maximum tilt toward or away from the sun is the December or June solstice.

Increasing greenhouse

Increasing greenhouse gases linked to rains over Africa thousands of years ago

A ring or circle of light around the sun or moon is called a halo by scientists.

The U.S. National Weather Service in Amarillo, Texas posted this photo on its Facebook page this weekend. Joshua Thomas in Red River, New Mexico captured these magnificent arcs in the sky on the morning of January 9, 2015. Look below for a labeled version of the same photo.

Ice halos are commonly seen by those who look at the skies; we receive several photos of ice halos from somewhere in the world every week, especially in wintertime. Often, we’ll receive many such photos, across a particular region, sometimes for several days in a row. Most ice halos appear as a circle or ring around the sun or moon. Sometimes, if conditions are just right, you do see these wonderful, rare events when the whole sky is filled with halo arcs.

Ice halos are caused by ice crystals in the upper atmosphere, which both refract and reflect sunlight or moonlight.

A ring or circle of light around the sun or moon is called a halo by scientists. We get many messages throughout each year from people who’ve just spotted a ring around the sun or moon. People want to know: what causes a halo around the sun or moon? Follow the links below to learn more about lunar and solar halos.

What makes a halo around the sun or moon?

If you see a halo, notice this!

What makes a halo around the sun or moon? There’s an old weather saying: ring around the moon means rain soon. There’s truth to this saying, because high cirrus clouds often come before a storm. Notice in these photos that the sky looks fairly clear. After all, you can see the sun or moon. And yet halos are a sign of high thin cirrus clouds drifting 20,000 feet or more above our heads.

These clouds contain millions of tiny ice crystals. The halos you see are caused by both refraction, or splitting of light, and also by reflection, or glints of light from these ice crystals. The crystals have to be oriented and positioned just so with respect to your eye, in order for the halo to appear.

That’s why, like rainbows, halos around the sun – or moon – are personal. Everyone sees their own particular halo, made by their own particular ice crystals, which are different from the ice crystals making the halo of the person standing next to you.

If you see a halo, notice this! Because moonlight isn’t very bright, lunar halos are mostly colorless, but you might notice more red on the inside and more blue on the outside of the halo. These colors are more noticeable in halos around the sun. If you do see a halo around the moon or sun, notice that the inner edge is sharp, while the outer edge is more diffuse. Also, notice that the sky surrounding the halo is darker than the rest of the sky.

Holuhraun lava field

Since August 2014, lava has gushed from fissures just north of Vatnajökull, Iceland’s largest glacier. As of January 6, 2015, the Holuhraun lava field had spread across more than 84 square kilometers (32 square miles), making it larger than the island of Manhattan. Holuhraun is Iceland’s largest basaltic lava flow since the Laki eruption in 1783–84, an event that killed 20 percent of the island’s population.

The Operational Land Imager (OLI) on Landsat 8 captured this view of the lava field on January 3, 2015. The false-color images combine shortwave infrared, near infrared, and red light (OLI bands 6-5-4). The plume of steam and sulfur dioxide appears white. Newly-formed basaltic rock is black. Fresh lava is bright orange. A lava lake is visible on the western part of the lava field, and steam rises from the eastern margin where the lava meets the Jökulsá á Fjöllum river.

For comparison, the lower image shows the size of the lava field as observed by Landsat 8 on September 6, 2014. Beyond the growth of the lava field, notice that much of the flow was in lava rivers on the surface in September, while in January much of the lava was delivered to the eastern edge through a closed channel.

Scientists from the University of Iceland’s Institute of Earth Sciences have estimated the thickness of the lava field based on data from surveillance flights. On average, the eastern part was about 10 meters (33 feet) thick, the center was 12 meters, and the western part was 14 meters. Their preliminary analysis put the volume of lava at 1.1 cubic kilometers, enough for the eruption to be considered a flood basalt.

While Holuhraun continues to spew copious amounts of lava and sulfur dioxide, some observations suggest the eruption may be slowing down. As Edinburgh University volcanologist John Stevenson noted on his blog, Icelandic scientists have shown that the sinking (subsidence) of the caldera has declined from 80 centimeters (31 inches) to 25 centimeters per day—a sign that less magma is moving toward the surface. In addition, magnitude 5 or higher earthquakes that used to occur daily are now happening about once a week. Meanwhile, satellite observations of heat flux show a decline from more than 20 gigawatts in early September to fewer than 5 gigawatts by the end of November.

“This doesn’t mean that the eruption will stop soon. Like the weakening spray from an aerosol can, the eruption rate declines exponentially. The lower the flow, the more slowly it declines,” said Stevenson. Some volcanologists have predicted lava could continue to flow for years.

The video below, shot by Stevenson, shows a University of Iceland scientist sampling an active lava flow. Orange-yellow material has a temperature of about 800 degrees Celsius (1,470 degrees Fahrenheit), but there is no danger that the steel in the shovel will melt because it has a melting point of about 1,400 degrees Celsius and steel is a poor conductor of heat. After collection, the sample was dropped into a large metal saucepan and quenched by pouring water into it. Analysis of these samples has confirmed that the magma originated in the Bardarbunga volcanic system and was last stored at a depth of 9 to 20 kilometers beneath the surface.

Diamonds found at or near Earth's surface

Diamonds found at or near Earth's surface have formed through four different processes. The plate tectonics cartoon above presents these four methods of diamond formation. Additional information about each of them can be found in the paragraphs and small cartoons below.

Methods of Diamond Formation

Many people believe that diamonds are formed from the metamorphism of coal. That idea continues to be the "how diamonds form" story in many science classrooms.

Coal has rarely played a role in the formation of diamonds. In fact, most diamonds that have been dated are much older than Earth's first land plants - the source material of coal! That alone should be enough evidence to shut down the idea that Earth's diamond deposits were formed from coal.

Another problem with the idea is that coal seams are sedimentary rocks that usually occur as horizontal or nearly horizontal rock units. However, the source rocks of diamonds are vertical pipes filled with igneous rocks.

Four processes are thought to be responsible for virtually all of the natural diamonds that have been found at or near Earth's surface. One of these processes accounts for nearly 100% of all diamonds that have ever been mined. The remaining three are insignificant sources of commercial diamonds.

These processes rarely involve coal.

1) Diamond Formation in Earth's Mantle

Geologists believe that the diamonds in all of Earth's commercial diamond deposits were formed in the mantle and delivered to the surface by deep-source volcanic eruptions. These eruptions produce the kimberlite and lamproite pipes that are sought after by diamond prospectors. Diamonds weathered and eroded from these eruptive deposits are now contained in the sedimentary (placer) deposits of streams and coastlines.

The formation of natural diamonds requires very high temperatures and pressures. These conditions occur in limited zones of Earth's mantle about 90 miles (150 kilometers) below the surface where temperatures are at least 2000 degrees Fahrenheit (1050 degrees Celsius) (1). This critical temperature-pressure environment for diamond formation and stability is not present globally. Instead it is thought to be present primarily in the mantle beneath the stable interiors of continental plates (2).

            Herkimer Diamonds

            Diamonds Don't Form From Coal

            Synthetic Diamonds

            Gem Diamond Producers

Diamonds formed and stored in these "diamond stability zones" are delivered to Earth's surface during deep-source volcanic eruptions. These eruptions tear out pieces of the mantle and carry them rapidly to the surface (3), See Location 1 in the diagrams above and at right. This type of volcanic eruption is extremely rare and has not occurred since scientists have been able to recognize them.

Is coal involved? Coal is a sedimentary rock, formed from plant debris deposited at Earth's surface. It is rarely buried to depths greater than two miles (3.2 kilometers). It is very unlikely that coal has been moved from the crust down to a depth well below the base of a continental plate. The carbon source for these mantle diamonds is most likely carbon trapped in Earth's interior at the time of the planet's formation.

2) Diamond Formation in Subduction Zones

Tiny diamonds have been found in rocks that are thought to have been subducted deep into the mantle by plate tectonic processes - then returned to the surface (4). (See Location 2 in the diagrams above and at right.) Diamond formation in a subducting plate might occur as little as 50 miles (80 kilometers) below the surface and at temperatures as low as 390 degrees Fahrenheit (200 degrees Centigrade) (1). In another study, diamonds from Brazil were found to contain tiny mineral inclusions consistent with the mineralogy of oceanic crust. (8)

Is coal involved? Coal is a possible carbon source for this diamond-forming process. However, oceanic plates are more likely candidates for subduction than continental plates because of their higher density. The most likely carbon sources from the subduction of an oceanic plate are carbonate rocks such as limestone, marble and dolomite and possibly particles of plant debris in offshore sediments.

3) Diamond Formation at Impact Sites

Throughout its history, Earth has been repeatedly hit by large asteroids. When these asteroids strike the earth extreme temperatures and pressures are produced. For example: when a six mile (10 kilometer) wide asteroid strikes the earth, it can be traveling at up to 9 to 12 miles per second (15 to 20 kilometers per second). Upon impact this hypervelocity object would produce an energy burst equivalent to millions of nuclear weapons and temperatures hotter than the sun's surface (5).

The high temperature and pressure conditions of such an impact are more than adequate to form diamonds. This theory of diamond formation has been supported by the discovery of tiny diamonds around several asteroid impact sites. See Location 3 in the diagrams above and at right.

Tiny, sub-millimeter diamonds have been found at Meteor Crater in Arizona. Polycrystalline industrial diamonds up to 13 millimeters in size have been mined at the Popigai Crater in northern Siberia, Russia. [7]

Is coal involved? Coal could be present in the target area of these impacts and could serve as the carbon source of the diamonds. Limestones, marbles, dolomites and other carbon-bearing rocks are also potential carbon sources.

4) Formation in Space

NASA researchers have detected large numbers of nanodiamonds in some meteorites (nanodiamonds are diamonds that are a few nanometers - billionths of a meter in diameter). About three percent of the carbon in these meteorites is contained in the form of nanodiamonds. These diamonds are too small for use as gems or industrial abrasives, however, they are a source of diamond material (6), See Location 4 in the diagrams above and at right.

Smithsonian researchers also found large numbers of tiny diamonds when they were cutting a sample from the Allen Hills meteorite (7). These diamonds in meteorites are thought to have formed in space through high speed collisions similar to how diamonds form on Earth at impact sites.

Is coal involved? Coal is not involved in the creation of these diamonds. The carbon source is from a body other than Earth.

The Most Convincing Evidence

The most convincing evidence that coal did not play a role in the formation of most diamonds is a comparison between the age of Earth's diamonds and the age of the earliest land plants.

Almost every diamond that has been dated formed during the Precambrian Eon - the span of time between Earth's formation (about 4,600 million years ago) and the start of the Cambrian Period (about 542 million years ago). In contrast, the earliest land plants did not appear on Earth until about 450 million years ago - nearly 100 million years after the formation of virtually all of Earth's natural diamonds.

Since coal is formed from terrestrial plant debris and the oldest land plants are younger than almost every diamond that has ever been dated, it is easy to conclude that coal did not play a significant role in the formation of Earth's diamonds.

The value of a diamond is based upon its Carat weight, Clarity, Color and the quality of its Cut. Most diamonds are in a color range that runs from clear to yellow to brown. Those that are colorless receive the highest grade and are generally of highest value.

fancy diamond "Fancy" Diamonds

A small number of natural diamonds fall outside of the typical white-yellow-brown color range. They can be pink, blue, purple, red, orange or any color. When they are a pleasing shade they can be extremely valuable and are given the name "fancy" diamonds.

colored diamond What Causes Colored Diamonds?

As in other gemstones, color variants in diamond can be caused by impurities, heat or irradiation. Nitrogen in the stone causes a yellow color. Irradiation can produce greens. Irradiation followed by heating can produce almost any color.

diamonds in mantle The Gem of Heat and Pressure

Diamonds are a high-temperature and high- pressure mineral. They do not form naturally at Earth's surface or at shallow depths. The conditions where they can form are in Earth's mantle at a depth of about 100 miles below the surface.

diamonds in mantle Carbon Polymorphs

Polymorph means "many forms". Diamond and graphite are polymorphs. They are both composed of carbon but have different properties. This results from the minerals having different crystal structures with different types of bonds between carbon atoms.

synthetic diamond Synthetic Diamonds for Industry

People have been able to manufacture diamonds since the 1950's. At first the cost was very high. Now, over 100 tons of diamonds are manufactured every year. Most of these diamonds are used to make cutting tools and abrasives.

synthetic diamond Synthetic Diamonds for Jewelry

People have successfully made gem-quality diamonds for use in fine jewelry. The stones are said to be undistinguishable from natural stones in a direct observation by experienced gemologists. They can be identified by laboratory tests.

meteorite diamondsDiamonds From Space!

Diamonds have been found in some meteorites and the impact of meteorites with Earth is thought to produce enough heat and pressure to transform carbon into diamonds.

octahedral diamondOctahedral Diamonds

Many uncut diamonds have a geometric shape. These are natural diamond crystals. A common crystal shape is the octahedron. This shape is similar to two four-sided pyramids connected at their base to form a geometric solid with eight faces.

diamond drill bitDiamonds For Drilling

Drilling oil and gas wells down through thousands of feet of rock requires a tough drill bit. Small diamonds are embedded into the cutting surfaces of these bits. The extremely hard diamonds wear away the rock as the drill bit is turned in the hole.

carbonOne Element Gemstone

Diamonds have a very simple composition. They are composed of carbon. Diamond is the only gemstone composed of just one element. Small amounts of other elements might exist in diamonds as impurities. These often give diamond a slight 

Rainfall can release aerosols

High-speed imaging captures raindrops releasing clouds of aerosols on impact.

Ever notice an earthy smell in the air after a light rain? Now scientists at MIT believe they may have identified the mechanism that releases this aroma, as well as other aerosols, into the environment.

Using high-speed cameras, the researchers observed that when a raindrop hits a porous surface, it traps tiny air bubbles at the point of contact. As in a glass of champagne, the bubbles then shoot upward, ultimately bursting from the drop in a fizz of aerosols.

The team was also able to predict the amount of aerosols released, based on the velocity of the raindrop and the permeability of the contact surface.

The researchers suspect that in natural environments, aerosols may carry aromatic elements, along with bacteria and viruses stored in soil. These aerosols may be released during light or moderate rainfall, and then spread via gusts of wind.

“Rain happens every day — it’s raining now, somewhere in the world,” says Cullen R. Buie, an assistant professor of mechanical engineering at MIT. “It’s a very common phenomenon, and it was intriguing to us that no one had observed this mechanism before.”

Youngsoo Joung, a postdoc in Buie’s lab, adds that now that the group has identified a mechanism for raindrop-induced aerosol generation, the results may help to explain how certain soil-based diseases spread.

“Until now, people didn’t know that aerosols could be generated from raindrops on soil,” Joung says. “This finding should be a good reference for future work, illuminating microbes and chemicals existing inside soil and other natural materials, and how they can be delivered in the environment, and possibly to humans.”

Buie and Joung have published their results this week in the journal Nature Communications.

Capturing a frenzy, in microseconds

Buie and Joung conducted roughly 600 experiments on 28 types of surfaces: 12 engineered materials and 16 soil samples. In addition to acquiring commercial soils, Joung sampled soil from around MIT’s campus and along the Charles River. He also collected sandy soil from Nahant Beach in Nahant, Massachusetts.

In the lab, the researchers measured each soil sample’s permeability by first pouring the material into long tubes, then adding water to the bottom of each tube and measuring how fast the water rose through the soil. The faster this capillary rise, the more permeable the soil.

In separate experiments, the team deposited single drops of water on each surface, simulating various intensities of rainfall by adjusting the height from which the drops were released. The higher the droplet’s release, the faster its ultimate speed.

Joung and Buie set up a system of high-speed cameras to capture raindrops on impact. The images they produced revealed a mechanism that had not previously been detected: As a raindrop hits a surface, it starts to flatten; simultaneously, tiny bubbles rise up from the surface, and through the droplet, before bursting out into the air. Depending on the speed of the droplet, and the properties of the surface, a cloud of “frenzied aerosols” may be dispersed.

“Frenzied means you can generate hundreds of aerosol droplets in a short time — a few microseconds,” Joung explains. “And we found you can control the speed of aerosol generation with different porous media and impact conditions.”

From their experiments, the team observed that more aerosols were produced in light and moderate rain, while far fewer aerosols were released during heavy rain.

Buie says this mechanism may explain petrichor — a phenomenon first characterized by Australian scientists as the smell released after a light rain.

“They talked about oils emitted by plants, and certain chemicals from bacteria, that lead to this smell you get after a rain following a long dry spell,” Buie says. “Interestingly, they don’t discuss the mechanism for how that smell gets into the air. One hypothesis we have is that that smell comes from this mechanism we’ve discovered.”

Infrared Orion from WIS

 The Great Nebula in Orion is an intriguing place. Visible to the unaided eye, it appears as a small fuzzy patch in the constellation of Orion. But this image, an illusory-color four-panel mosaic taken in different bands of infrared light with the Earth orbiting WISE observatory, shows the Orion Nebula to be a bustling neighborhood or recently formed stars, hot gas, and dark dust. The power behind much of the Orion Nebula (M42) is the stars of the Trapezium star cluster, seen near the center of the above wide field image. The orange glow surrounding the bright stars pictured here is their own starlight reflected by intricate dust filaments that cover much of the region. The current Orion Nebula cloud complex, which includes the Horsehead Nebula, will slowly disperse over the next 100,000 years