This report assists homeowners in understanding why expansive soils shrink and heave and how excessive shrinking and heaving can be moderated. It also attempts to define the difference between cosmetic damage and structural damage resulting from expansive soil movement. The characteristics of expansive soils are discussed, as well as how they affect buildings. AØsection includes questions most frequently asked by persons who have or are building homes on expansive soils and the answers they seek.
Commencing with a brief introduction to mineral systems, and the properties of minerals in plane-polarised and cross-polarised light, the mineral key also includes line drawings, tables of mineral properties and an interference colour chart, to further aid mineral identification. To minimise the chance of misidentification, and enable less experienced petrologists to use the key with confidence, the key has been arranged to prioritise those properties that are most easily recognised.
Designed for simplicity and ease of use, it is primarily aimed at undergraduate and postgraduate students of mineralogy and petrology, but should also provide a valuable source of reference for all practising geologists dealing with rock thin sections and their interpretation.