Kvartsandel

Kvartsandel is a mineralogical term used to describe the quartz fraction of a rock or sediment. In Swedish geological literature, kvartsandel refers to the proportion of quartz by volume (often expressed as a percentage) and is used to characterize composition, aid classification, and interpret formation processes. The concept is relevant across petrology, sedimentology and mineral resources.

Measuring kvartsandel can be done through several methods. In petrography, thin-section analysis with point counting provides an estimate of quartz abundance relative to other minerals. More quantitative approaches include X-ray diffraction (XRD) with Rietveld refinement or quantitative image analysis of scanned sections, which can yield volume fractions of quartz and other phases. Modern automated mineralogy tools can combine imaging with mineral recognition to determine kvartsandel.

The kvartsandel of a rock or sediment has implications for its properties and history. In sedimentary rocks, quartz content is a key factor in maturity and textural classification; quartz-dominated sands are often described as quartz arenites, whereas rocks with substantial feldspar or lithic fragments are termed arkoses or lithic sandstones, respectively. In igneous and metamorphic rocks, the quartz fraction influences overall composition and texture, contributing to terms like felsic in igneous rocks and quartz-rich textures in metamorphic rocks such as quartzite. Kvartsandel also affects physical properties relevant to practical uses, including hardness, porosity and permeability.

Etymologically, the term reflects its Swedish usage and is commonly encountered in Scandinavian geological literature. In English-language contexts, kvartsandel is usually referred to as quartz fraction or quartz content.