Читать книгу Geology and Mineralogy of Gemstones - Karl Wallace, David Turner R. - Страница 13

In order to understand the world of gemstones and their geological origins, we first need to build a foundation by learning about some mineralogy concepts. Mineralogy, in its most basic definition, is a branch of science concerned with the study of minerals. Though seemingly a fairly narrow topic, mineralogy reaches far into a number of other disciplines from medicine (e.g., effects of mineral fibers on lungs) to ceramics (e.g., firing of clay‐based pottery) and the origins of the Earth itself (e.g., mineral inclusions trapped in diamonds). This book focuses on understanding the geological origin of gemstones, most of which are natural materials known as minerals and are found within rocks. Before deciphering their origins, we must understand gemstones as minerals.

A lengthy yet concise definition of the term mineral is:

A mineral is a (i) naturally occurring, (ii) solid with a (iii) definite (but generally not fixed) chemical composition, and a (iv) crystalline structure. It is usually formed by (v) inorganic processes.

The International Mineralogical Association lists 5,673 distinct mineral species as of early 2021 and there is active research to understand how the diversity of mineral species has changed through time (Hazen et al., 2015). Rocks can essentially be thought of as (i) naturally occurring aggregates of (ii) one or more mineral species held together through interlocking grains. It is important to note that rocks and minerals are natural solids and usually formed by inorganic processes. Materials made by people in a laboratory or elsewhere, such as synthetic crystals, would therefore not qualify as rocks or minerals though may share some similar properties. Since most gems are minerals, this clearly defined way of looking at minerals allows us to easily differentiate a valuable ruby gemstone from common red glass.