Lithology description covers macroscopic observation of qualitative rock properties. This data may come from several sources recorded for different purposes. It may include different descriptions from a single or multiple authors under various conditions or over time. These properties rely on interpretation and may include subjective impressions based on experience of the geologist. Often this written text follows a distinct pattern of standard observations within a structured code supported formula.
One common convention structures an ordered description by; Rock Type, Color, Texture, Cement of Matrix, Accessories, Fossils, Sedimentary Structures, Porosity, and Shows. This format is suitable for standardized queries and can be supported by established reference data sets. Conversely more detailed descriptions may be expressed as free form text or descriptive narrative that focus on specific issues or specialized characteristics. Both these approaches to Lithology are supported and are arbitrarily divided into the classes LITHOLOGY and LITHOLOGY_REMARKS.
One of the first issues when describing lithology is dealing with mixed lithology samples. Many rocks are a combination of rock types, both sand and shale for instance. The Lithology description can address the rock as a whole or break the description down into separate descriptions of specific parts. In the sand and shale example, there may be a LITHOLOGY description of a �sand and shale� ROCK_SAMPLE and there may be additional LITHOLOGY descriptions of a �sand component� of the sand ROCK_SAMPLE_FRACTION and a �shale component� of the shale ROCK_SAMPLE_FRACTION.