Describe and explain the factors that control metamorphism. Describe and explain the mineral reactions that occur as smectite-rich mud becomes buried to depths of thousands of meters in a sedimentary basin. Describe and explain the relationships between oil and mudrocks, and the processes by which an oil reservoir develops. Describe and explain the crystalline structures, chemical compositions, and structure-composition relations in the pyroxene group minerals. Briefly explain the petrologic significance of this diagram.
Silicate minerals are the most abundant mineral group in the Earth's crust.
Together, by atomic abundance, they comprise about 84 percent of the crust. Most of the oxygen in the crust combines in this way with silicon. Thus, nearly 84 percent of the atoms in the Earth's crust make up the -4 charged silicate tetrahedra. All 6 of the remaining abundant elements in the crust are cations. Because the -4 charged silicate tetrahedra are so abundant, most of the remaining cations in the crust combine with the tetrahedra to neutralize their charges.