Peridotite

Definition

Peridotite is a type of igneous rock that is composed primarily of the mineral olivine, along with varying amounts of other minerals such as pyroxene and spinel. It is a dense, coarse-grained rock that is typically green or yellow-green in color and is found in the Earth's mantle and upper crust.

5 Must Know Facts For Your Next Test

1. Peridotite is one of the most abundant rock types in the Earth's mantle, making up a significant portion of the upper mantle.
2. The high magnesium content of peridotite makes it dense and resistant to weathering, contributing to its prevalence in the Earth's interior.
3. Peridotite is often associated with the formation of diamonds, as the high-pressure and high-temperature conditions in the mantle can lead to the crystallization of diamonds.
4. The alteration of peridotite by hydrothermal fluids can result in the formation of serpentinite, a softer, more hydrated rock.
5. Peridotite is an important source of chromium, nickel, and platinum group elements, which are valuable industrial and economic resources.

Review Questions

• Describe the composition and physical properties of peridotite.
  • Peridotite is a dense, coarse-grained igneous rock that is primarily composed of the mineral olivine, along with varying amounts of other minerals such as pyroxene and spinel. The high magnesium content of peridotite gives it a distinctive green or yellow-green color and makes it resistant to weathering. Peridotite is one of the most abundant rock types in the Earth's mantle, contributing to its overall density and prevalence in the planet's interior.
• Explain the relationship between peridotite and the formation of diamonds.
  • The high-pressure and high-temperature conditions in the Earth's mantle, where peridotite is abundant, can lead to the crystallization of diamonds. As peridotite is altered and subjected to these extreme conditions, the carbon present in the rock can undergo phase changes and form diamond crystals. This association between peridotite and diamond formation is an important factor in the exploration and extraction of these valuable gemstones.
• Discuss the economic and industrial significance of peridotite.
  • Peridotite is an important source of several valuable mineral resources, including chromium, nickel, and platinum group elements. These elements are in high demand for various industrial and economic applications, such as the production of stainless steel, catalytic converters, and jewelry. The alteration of peridotite can also lead to the formation of serpentinite, which has its own set of industrial uses. The abundance and composition of peridotite make it a crucial rock type in terms of its economic and industrial importance.

Related terms

Olivine:

A silicate mineral that is the primary component of peridotite, composed of magnesium and iron.

Pyroxene:

A group of silicate minerals that can be found in peridotite, contributing to its composition.

Spinel: A group of oxide minerals that can be present in peridotite, often as a minor component.