Story of Diamond | How it forms | GeologyConcepts.com

Summary

This transcript explores the fascinating process of diamond formation, particularly focusing on how diamonds are created deep within the Earth and later brought to the surface. It delves into geological concepts like volcanic intrusions, pressure, temperature, oxidation, and reduction conditions that influence the creation of diamonds. The script also explains how diamonds, formed millions of years ago, can be transported through kimberlite pipes and brought to the surface in places like Kimberley, South Africa. The process involves intricate details about carbon, oxygen, and their roles in diamond's crystallization and how these diamonds can reach the Earth's surface despite the challenging conditions.

Takeaways

• 😀 Diamonds are formed under extreme pressure and temperature conditions in the Earth's mantle.
• 😀 Kimberlite pipes, formed from volcanic eruptions, are key to bringing diamonds to the surface.
• 😀 Diamonds are not formed in kimberlite pipes themselves, but are transported from deeper, older rocks.
• 😀 The creation of diamonds requires a reducing environment, where carbon can form into crystals without being oxidized.
• 😀 The process of diamond formation involves the conversion of graphite into diamond under high pressure.
• 😀 The pressure-temperature conditions at different depths in the Earth's mantle affect the stability of graphite and diamond.
• 😀 Carbon is necessary for diamond formation, but oxygen must be reduced for diamonds to form effectively.
• 😀 Kimberlite rocks, where diamonds are often found, are not uniformly young but can contain diamonds that are billions of years old.
• 😀 Diamonds can be found in old cratonic areas, like the ones in Panna and Bundelkhand in India, and South Africa's Kimberley.
• 😀 The transformation from graphite to diamond is a slow, energy-intensive process that can take millions to billions of years.
• 😀 Diamonds brought up by volcanic plumes might be unstable and gradually convert to graphite if they reach the surface slowly.

Q & A

What is the significance of Kimberley in the context of diamonds?

Kimberley is a location in South Africa where volcanic pipes, known as kimberlite pipes, contain diamonds. These pipes are important as they are the source of diamonds found in the region, and Kimberley became famous for its diamond mining operations.

What is a kimberlite pipe, and how does it relate to the formation of diamonds?

A kimberlite pipe is a type of volcanic pipe formed by volcanic eruptions that bring material from the Earth's mantle to the surface. These pipes contain diamond-bearing material, which is how diamonds are brought up from deep within the Earth.

Why do geologists study kimberlite pipes?

Geologists study kimberlite pipes to understand the conditions under which diamonds form. The study helps in determining the age of the rocks and the process of how diamonds and other minerals were transported to the Earth's surface.

How do diamonds form in the Earth's mantle?

Diamonds form in the Earth's mantle under high pressure and temperature conditions. Graphite, a stable form of carbon, can convert into diamond when the pressure increases. The process happens deep within the mantle, where conditions are suitable for diamond formation.

What is the 'diamond-graphite line' mentioned in the script?

The 'diamond-graphite line' refers to the boundary in the Earth's mantle where the pressure is high enough to stabilize diamonds below it but causes graphite to remain stable above it. The line is not straight because pressure varies with depth in the mantle.

Why does the line between diamond and graphite not remain straight?

The line between diamond and graphite is not straight because the pressure in the Earth's mantle varies with depth. The increase or decrease in pressure influences the stability of graphite and diamonds, causing the line to curve.

What role does oxygen concentration play in diamond formation?

Oxygen concentration plays a crucial role in the oxidation-reduction conditions of the mantle. Diamonds require a reduced environment with low oxygen to form. In regions with high oxygen, carbon will remain in the form of CO2 instead of forming diamonds.

Why is carbon important for diamond formation?

Carbon is the key element in the formation of diamonds. However, it needs to be in a reduced form, free from oxidation, for diamonds to form. The carbon must come from regions where the conditions are suitable for the creation of diamonds instead of graphite or CO2.

What happens to diamonds when they rise to the Earth's surface?

As diamonds rise to the surface through volcanic eruptions, they can slowly begin to convert into graphite due to the lower pressure and temperature. However, this conversion is very slow and occurs over millions of years.

Why is it rare to find diamonds on the surface of the Earth?

Diamonds are rare on the Earth's surface because they are typically found in kimberlite pipes that bring them from deep within the mantle. The diamonds that do surface are often very old and have taken millions of years to reach the upper layers.