ERTH 2102 Lecture Notes - Lecture 45: Crystal System, Orthorhombic Crystal System, Tetragonal Crystal System

• School: Carleton University
• Department: Earth Sciences
• Course: ERTH 2102
• Professor: Fred Gaidies

Document Summary

Minerals are classified based on anion/anionic group and crystal structure. Minerals are identified using their physical properties and crystal structure using hand specimens and thin sections. Inorganic [ cannot be formed by living things & are without c-c bonds ] Naturally occuring [ formed by natural processes ] Only about 8 minerals compose of about 98% of the earth"s crust. 8 elements form the building blocks of most rock-forming minerals. The tetrahedron is the most fundamental building block of minerals. Ferric iron ( fe3+ ) is larger than ferrous iron ( fe2+) [ the larger the ion, the more the cloud can pull in therefore compacting the ion making it smaller in size ] Pressure ( p ) and temperature ( t ) influence cation/anion size ratio and coordination number. Isometric [ the cubic crystal system, has angles are right angles and a=b=c isotropic ] Tetragonal [ has right angles, sides are not equal a=b c anisotropic ]