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The Rarest Rocks in the World

5 Rocks You Probably Won’t Find in Your Backyard

There are three basic types of rock in the world and they are classified according to how they are formed.  They are igneous rocks (formed from molten rock beneath the earth’s crust); sedimentary rocks (formed by the accumulation of sediment over geological time which is then compressed to form the rock), and finally, metamorphic rock (which is any kind of rock which is then subjected to extremes of heat and pressure which changes the chemical and physical features of the original rock).

Rock is being formed everywhere all of the time, but some rock is much rarer than others – in some cases, extremely rare.

The Rarest Rock of All

The rarest rock in the world is probably the rock formed preserved from the earth’s original crust when it was created billions of years ago.  To date, only two pieces have ever been found; the first piece was discovered in Canada in 2008 and the second piece in India in 2009.

The rocks date back to around 4 billion years ago, and were formed from cooling magma which eventually formed the primeval crust of the newly formed Earth when the solar system was initially being formed.

Martian Meteorites

martian meteorite

Running second in the listing of the world’s rarest rocks must be the Martian meteorites which have been found scattered around the world.  They are exceedingly rare because they have come all the way from the planet Mars!  The fact that we don’t have to go to mars to study Martian rocks surprises many people, however the Earth has been bombarded with bits of leftover solar system for billions of years.

This said, the Martian meteorites are typically igneous rocks because they have been blasted off the face of the planet by volcanic eruptions, some as old as the oldest rocks formed originally on our own planet.

Obicular Granite

orbicular-granite

The rarest rocks originate at the deepest depths of the Earth’s mantle; the mantle is the molten coating which surrounds the core of our planet.  Rocks from these very deep depths are referred to as “Plutonic” because they are formed at depths associated with hell and Pluto was the Roman god of the underworld.

Obicular granite is a plutonic rock which is found in only a very few locations around the world.  Outcrops have been discovered in two locations in Chile, one in Finland and recently, in a quarry in Connecticut.

It’s highly unlikely you’ll be finding this granite forming your kitchen counter tops anytime soon.

Carbonaceous Chondrites

Carbonaceous-chondrites

These are another extra-terrestrial visitor, but this time from the remnants of the material which was left over when the sun and the planets were initially formed.  They are extremely rare and come with diamonds and sapphires which were formed before the solar system itself.  They are extremely old; older than any rocks indigenous to the Earth itself and were formed around stars which themselves blew up and provided the original raw material to form our own sun.

Carbonatites

Carbonatite

Carbonatites are very rare, with only around 300 localities known to produce them.  They are igneous rocks, i.e. formed from volcanic activity or deep within the bowels of the molten earth, and what makes them rare is their chemical composition.  They contain a high level of carbon as opposed to silicon, and this makes for unusual rock formations when they are formed.

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Posted by on September 9, 2010. Filed under Science, The List. You can follow any responses to this entry through the RSS 2.0. Both comments and pings are currently closed.

2 Responses to The Rarest Rocks in the World

  1. i love thos rocks

  2. Could you imagine having the Obicular Granite has a countertop? Beautiful!