An extremely rare refractory metal, rhenium is most often found in superalloys, alloys that are extremely durable and resist deformation at high temperatures, such as those used jet turbine engines.

One of the more unique uses for rhenium, however, has been in dart barrels. Rhenium's use in darts began not because of its heat resistance or strength, but because of its density.

Rhenium is amongst the most dense metal elements (it is only surpassed in weight by iridium and platinum), which means that rhenium dart barrels have the smallest mass to weight ratio available of any dart. (Actually the barrels are made of a tungsten-rhenium alloy containing about 5% rhenium).

The increased density allows for a sleeker, thinner design that theoretically - although I don't know that it would my game much - leaves more space to hit three treble 20s.

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Ruthenium has never been a metal that stole the spotlight. Mostly used in the production of computer hard disks, only about 30 metric tonnes of the metal are produced each year.

It's first major commercial application came about in the mid-1940s, strangely enough, in fountain pens.

The Parker 51, the Parker Pen Company's most successful pen, which - complete with gold and chrome plating - was marketed towards bankers, businessmen and politicians, sold at a rate of 2.1 million units per year in 1947.

One of the keys to the success of the Parker 51 was its tip, which had to be made from a hard, durable metal that would not deform under the friction of writing.

After initially using an alloy of osmium and iridium, the company turned to ruthenium in 1944, not necessarily because it performed any better, but because it was more readily available and cheaper, making it the first ruthenium tipped pen.

Ruthenium continues to be used in pen tips to this day. Read More...

The world's second largest steel maker, Baosteel, saw its net profits drop by over 40% in 2011.

The Fortune 500 company had net profits of 7.36 billion yuan (US$ 1.67 billion) last year, despite its gross revenue rising 10% over the same period to 222.86 billion yuan.

China's steelmakers have been feeling pressure from increasing raw material prices, which has led to recent efforts to set-up the first spot iron ore market.

Having already touched the ocean floor, metals exploration is looking to move into the final frontier: Space.

Planetary Resources Inc., founded by space tourism entrepreneurs Eric Anderson and Peter Diamandis, is raising money in order to take the first step in moving exploration into space. Within two years they hope launch reconnaissance telescopes that would examine thousands of asteroids closely orbiting the earth.

Asteroids can be contain higher levels of platinum group metals (PGMs), including platinum, palladium and rhodium, than any ore bodies in the earth's crust. They can also be made-up of nickel, iron and water.

The company's vision is simple: To bring the natural resources of space within humanity's economic sphere of influence.

While I don't know if the cost of 'space mining' makes such an adventure profitable today, it is not unfathomable that space exploration will play a part in solving issues of resource depletion in the future.