Olivine

Definition

Olivine is a magnesium iron silicate mineral that is commonly found in igneous rocks and is known for its distinctive green color. It plays a crucial role in the classification of minerals based on their chemical composition and crystal structure, often occurring in volcanic rocks and contributing to the formation of the Earth's mantle.

5 Must Know Facts For Your Next Test

1. Olivine has a chemical formula of (Mg,Fe)2SiO4, indicating that it contains both magnesium and iron.
2. This mineral is often associated with ultramafic rocks, which are low in silica and high in magnesium and iron.
3. Olivine can form solid solutions, meaning it can exist with varying proportions of magnesium and iron, resulting in different varieties such as forsterite (high magnesium) and fayalite (high iron).
4. In addition to its role in geology, olivine is also used as a gemstone, known as peridot, which is valued for its vibrant green color.
5. Olivine's presence in magma can influence the viscosity and temperature of volcanic eruptions, affecting the overall volcanic activity.

Review Questions

• How does the chemical composition of olivine influence its classification within silicate minerals?
  • Olivine's classification as a silicate mineral is primarily due to its chemical composition of silicon and oxygen combined with magnesium and iron. The presence of these elements not only defines its physical properties but also places it within the broader category of silicate minerals. This classification helps geologists understand the conditions under which olivine forms and its relationship to other silicate minerals found in various rock types.
• Discuss the significance of olivine in understanding the formation of igneous rocks and the Earth's mantle.
  • Olivine is a key mineral for understanding the formation of igneous rocks as it is commonly found in many volcanic rocks, especially those formed from high-temperature magma. Its presence indicates the type of magma that produced the rock, often suggesting a more mafic or ultramafic composition. Additionally, olivine is abundant in the Earth's mantle, providing insight into the mantle's composition and conditions under which it forms, thus helping scientists to understand geochemical processes at depth.
• Evaluate the impact of olivine on volcanic activity and how this mineral can inform predictions about eruptions.
  • Olivine plays a crucial role in volcanic activity by influencing the properties of magma. Its presence can lower magma viscosity, allowing gases to escape more easily during an eruption. Understanding olivine's role helps geologists predict potential eruption styles—more explosive eruptions might occur when olivine-rich magma traps gas, leading to increased pressure. By studying olivine content in volcanic rocks, scientists can assess past eruption behavior and better forecast future volcanic events based on changes in olivine concentration.

Related terms

Igneous Rocks: Rocks formed through the cooling and solidification of magma or lava, where olivine is often found as a primary mineral.

Silicate Minerals:

A large group of minerals that contain silicon and oxygen as their main components, with olivine being a member due to its silicate structure.

Peridotite: A dense, coarse-grained igneous rock that is rich in olivine, typically found in the Earth's upper mantle.