Mineral Evolution

Introduction

• Earth has approximately 4300 known minerals, with around 50 new types identified annually.

• Diversity of near-surface minerals evolves over 4.5 billion years due to physical, chemical, and biological processes.

• Objective: Review significant changes in mineral diversity and distribution on Earth.

Key Concepts of Mineral Evolution

Process Overview

• Mineral evolution involves:

  • Gravitational clumping into protoplanetary disks.

  • Thermodynamic conditions and core formation.

  • Aqueous alteration and sediment processes.

  • Biological influences on mineral diversity.

Principal Stages of Mineral Evolution

1. Planetary Accretion (>4.55 Ga)

   • Formation of chondritic minerals in dense molecular clouds.

   • Clumping leads to chondrules and calcium-aluminum inclusions (CAIs).

   • ~60 primary minerals identified in chondrites.

2. Planetesimal Alteration (4.56 to 4.55 Ga)

   • Alteration and differentiation result in ~250 minerals from various meteorite types through aqueous, thermal, and shock processes.

3. Crust and Mantle Reworking (4.55 to 2.5 Ga)

   • Formation of diverse igneous rocks; increase to 1500 known minerals due to volcanic activity, outgassing, and subduction processes.

4. Biologically Influenced Mineralogy (>2.5 Ga)

   • Rise of life changes surface conditions; emergence of banded iron formations (BIFs) and carbonate deposits.

   • The Great Oxidation Event (~2.2 to 2.0 Ga) fundamentally changes atmospheric composition and mineral deposition.

Mechanisms Driving Mineral Evolution

1. Separation and Concentration

   • Redistribution of elements from uniform distribution to localized compositions.

   • Birth of minerals correlates with specific environmental conditions.

2. Intensive Variables

   • Variations in temperature, pressure, and volatile activities (H2O, CO2, O2).

   • Dramatically change mineral formation conditions.

3. Biological Processes

   • Living organisms create new pathways for mineral formation and significantly influence mineral diversity.

   • Biological activity results in localized reactions, supporting unique mineral formations not seen in abiotic environments.

Implications of Mineral Evolution

• Synthesizing mineralogical data into a coherent chronology provides historical context for Earth’s development.

• Understanding the role of minerals in life’s origins informs approaches to searching for life on other planets.

• The interaction of geologic time with mineral diversity offers a compelling framework for teaching and understanding mineral sciences.

Conclusion

• The dynamics of mineral evolution enhance the understanding of planetary histories and the role of life in shaping mineral diversity on Earth and beyond.

• A new framing of mineralogy that emphasizes evolutionary processes can invigorate the study and teaching of mineral science.