How Diamonds Form DDGA4

Metamorphic rock

A category of ricks that have been altered by heat and pressure. (eclogite)

Igneous rock

A category of rocks formed from a molten state. (Peridotite)

Pipe

A deep verticle formation at the earth's surface that results from a kimberlite or lamproite emplacement.

Emplacement

A geologic process that delivers materials (sometimes diamonds) to the surface.

Kilobar

A unit that scientists use to measure extremely high pressure. The normal,everyday pressure on earth at sea level is about one bar, and a kilobar is 1,000 times that. Diamond = 45 kilobars (45,000 times normal pressure.

Cratons

Acient, large, and stable parts of the earth's continental crust.

Kimberlite

An igneous rock that transports diamonds to the surface.

Lamporite

An igneous rock, rather than kimberlight, that transports diamonds to the surface.

Key Concept 1

Diamond and graphite are both made of carbon

Key Concept 2

Diamond's form in cratons, which are located only under continental landmasses.

Key Concept 4

Diamonds might wait hundreds of millions of years before they're carried to the surface.

Key Concept 5

Diamonds that exist today were delieved to the surface between 2.5 billion and 20 million years ago.

Core

Earth's innermost layer.

Difference between Kimberlite and Lamproite

while kimberlite tends to occur in the middle of cratons, lamproite is commonly found at the edges of cratons, or even in the zones immediately around them.

Key Concept 6

Kimberlites and lamproites transport diamonds to the surface, but diamonds don't form in them.

Mantle

Layer between the earth's crust and its core.q

Subduction

Process in which two crustal plates collide, forcing one under the other.

Key Concept 3

The carbon needed for diamond formation is always present.

Key Concept 7

Very few kimberlites actually contain diamonds.

Crust

The surface and outermost layer of the earth.