Olivine

Definition

Olivine is a common silicate mineral composed mainly of magnesium and iron, with the formula (Mg,Fe)₂SiO₄. It is a significant component of the Earth's upper mantle, playing a crucial role in mantle dynamics and the formation of igneous rocks. This mineral's unique properties influence its behavior in various geological processes, including magma generation and differentiation.

5 Must Know Facts For Your Next Test

1. Olivine is typically green in color due to its iron content, with variations in hue depending on the magnesium-to-iron ratio.
2. This mineral is highly resistant to weathering and is commonly found in mafic and ultramafic rocks, such as basalt and peridotite.
3. Olivine can dissolve in melts at high temperatures and pressures, influencing mineral solubility in magma.
4. It crystallizes early from a cooling magma due to its high melting point, making it important for understanding magmatic differentiation.
5. In mantle convection, olivine plays a critical role by influencing the physical properties of the mantle and the movement of tectonic plates.

Review Questions

• How does olivine contribute to our understanding of mantle composition and dynamics?
  • Olivine is a major constituent of the Earth's upper mantle and helps scientists understand mantle composition due to its abundance. Its presence indicates high-temperature conditions and influences mantle dynamics by affecting the viscosity and convection patterns. Studying olivine's properties helps geochemists model processes like melting and crystallization within the mantle, providing insights into tectonic movements.
• Discuss the significance of olivine's solubility in melts and its implications for magma generation.
  • Olivine's solubility in melts at varying temperatures and pressures has significant implications for magma generation. As magma rises towards the surface, changes in pressure can cause olivine to dissolve or crystallize, impacting the overall composition of the melt. Understanding this solubility helps geologists predict which minerals will form during different stages of magma evolution, influencing volcanic activity and the types of igneous rocks produced.
• Evaluate how olivine influences magmatic differentiation processes during volcanic eruptions.
  • Olivine plays a crucial role in magmatic differentiation during volcanic eruptions by crystallizing early from magma due to its high melting point. This early crystallization removes magnesium and iron from the melt, changing its composition over time. As different minerals crystallize at different temperatures, studying olivine allows geologists to reconstruct the history of magma evolution, understand eruption styles, and predict future volcanic behavior based on how these processes affect rock formation.

Related terms

Peridotite:

A dense, coarse-grained igneous rock consisting primarily of olivine and pyroxene, which forms the Earth's mantle.

Magma: A molten rock mixture found beneath the Earth's surface that can solidify to form igneous rocks when it cools.

Fractional Crystallization:

A process where different minerals crystallize from magma at different temperatures, affecting the composition of the remaining liquid.