Lecture 7 - Crystallization recorded

Overview of Crystallization
- Focus on nucleation of minerals.
- Changes in textures with varying conditions during nucleation and crystallization.
- Understanding mechanisms to differentiate magmas.
Key Takeaways
- Process of crystallizing magma.
- Review of Bowen's reaction series and its importance in fractionation.
- Discussion of supercooling and its effect on mineral habits.
- Behavior of solids and magmas in differentiating magma.
Mechanisms of Magma Differentiation
- Changing the Source: Impact of depth in the Earth on melt formation leading to varied rock types.
- Fractionation: Definition and cultural context of separating solids from a liquid.

Lunar Samples Collected by Apollo Missions
- Discovery of rounded balls of volcanic glass, identified as basalt; implications for geological understanding of the moon's history.
- The glass exhibits acicular (needle-like) textures visible under a microscope.
Formation and Characteristics of Lunar Basalt
- High-iron and magnesium composition of the basalt.
- The moon's geological history includes volcanism resembling historical eruptions on Earth.
- Rapid cooling eliminates traditional mineral habits due to the vacuum of space.
Bowen's Reaction Series Review
- Key contributor to understanding crystallization sequences in basalts.
- Overview of the crystallization sequence: olivine, pyroxene, amphibole, micas, up to quartz.

Introduction to Fuji Water
- Origin and low Total Dissolved Solids (TDS) level compared to tap water, impacting taste.
- Bottled at low temperatures, allowing supercooling phenomena.
Supercooling Experiment with Fuji Water
- Behavior of water at -10 to -15°C, remaining liquid until disturbed.
- Disturbances cause nucleation, exemplified by ice crystal formation in supercooled liquids.
Concept of Nucleation
- Nucleation points facilitate mineral growth under specific conditions.
- Influence of temperature, pressure, and composition on nucleation processes.

Conditions Affecting Nucleation
- Pressure: Opening a soda bottle releases CO2 due to pressure change.
- Time: Nucleation occurs at different rates over time; example: opened soda going flat.
- Catalysts: Introducing Mentos in Coke accelerates CO2 release due to increased surface area.
Implications for Magma
- Rate of mineral growth and nucleation in magmas changes with external conditions.

Nucleation and Growth Dynamics
- Effects of temperature on nucleation rates as magma cools.
- Temperature Conditions:
  - Temperature A: Low nucleation, high growth at stable conditions.
  - Temperature B: High nucleation, low mineral growth due to diffusion limitations.
  - Temperature C: Rapid cooling prevents nucleation and growth, leading to glass formation.

Formation of Glass
- Rapid cooling can result in volcanic glass such as obsidian.
- The relationship between nucleation size and cooling efficiency affecting mineral size.

Gravitational Fractionation
- Process where denser minerals separate from less dense magma during cooling.
- Evidence from geological sites showing the different layers of rock formed during fractionation.
Use of Stokes' Law
- Calculation of settling velocity of minerals in magma.
- Comparison of olivine settling in basalt vs. hornblende in rhyolite indicating significant differences in behavior and cooling times.

Fluid Behavior of Magmas
- Magmas transition from being Newtonian to Bingham plastics, requiring different forces for movement.
- Emphasizing the significance of yield stress and its relevance to mineral movement in various magma compositions.