Olivine

Definition

Olivine is a magnesium iron silicate mineral that is typically green in color and is one of the most abundant minerals in Earth's upper mantle. It plays a crucial role in understanding Earth's structure and composition, as it contributes to the formation of igneous rocks and helps to reveal information about mantle dynamics and the conditions under which rocks form.

5 Must Know Facts For Your Next Test

1. Olivine crystallizes in a cubic system and is commonly found in mafic and ultramafic rocks, particularly in basalt and peridotite.
2. It has a high melting point, making it stable at high temperatures, which is significant for understanding the conditions in the Earth's mantle.
3. Olivine can vary in composition, with forsterite (Mg2SiO4) being the magnesium-rich end member and fayalite (Fe2SiO4) being the iron-rich end member.
4. The presence of olivine in volcanic rocks can indicate the source of magma and its evolution as it ascends through the crust.
5. Olivine is also used as a refractory material due to its high resistance to heat, making it valuable in industrial applications.

Review Questions

• How does olivine's composition affect its role in understanding mantle processes?
  • Olivine's composition, primarily made up of magnesium iron silicate, directly influences its stability under high-temperature conditions found in the mantle. The variation between forsterite and fayalite can indicate different processes occurring within the mantle, such as temperature and pressure changes. Understanding these compositional differences helps geologists interpret mantle dynamics and the formation of igneous rocks.
• Discuss the significance of olivine in the study of igneous rock formation and what it reveals about Earth's interior.
  • Olivine is significant because it is one of the primary minerals found in many igneous rocks, especially those derived from the mantle. Its presence indicates that the rock has experienced conditions characteristic of deep Earth environments. By studying how olivine crystallizes and its subsequent alteration during rock formation, scientists can gain insights into the thermal history and composition of Earth's interior, shedding light on geological processes over time.
• Evaluate the implications of olivine's stability at high temperatures on our understanding of tectonic activity and volcanic eruptions.
  • Olivine's stability at high temperatures suggests that it plays a critical role during tectonic activity and volcanic eruptions. As magma ascends from the mantle to the surface, olivine can crystallize under varying pressures and temperatures. Analyzing olivine's behavior during these processes helps geologists predict volcanic activity and understand how different rock types evolve as they move through Earth's crust. This knowledge enhances our understanding of tectonic mechanisms and contributes to models that explain volcanic eruption patterns.

Related terms

Igneous Rock: A type of rock formed through the cooling and solidification of molten material, including both intrusive and extrusive varieties.

Mantle: The layer of Earth located between the crust and the core, composed mainly of silicate minerals and responsible for tectonic activity.

Peridotite: A dense, coarse-grained igneous rock composed primarily of olivine, along with pyroxene and other minerals, often found in the Earth's upper mantle.