Hydroxylbearing

Hydroxylbearing is an adjective used in mineralogy and geology to describe minerals or materials that contain hydroxyl groups (−OH) integrated into their crystal structure or present as structural water. In these substances, the OH groups are an essential part of the mineral’s chemistry rather than merely adsorbed moisture.

Hydroxyl-bearing minerals occur widely in the Earth’s crust and mantle. Common examples include serpentine minerals, talc, and phyllosilicates such as muscovite and biotite, as well as amphiboles. The hydroxyl content varies with composition and formation history, and the presence of OH groups reflects hydrous pathways during crystallization or alteration.

Formation and significance: OH-bearing minerals form through crystallization from aqueous fluids or by metamorphic and hydrothermal alteration that introduces water into existing mineral frameworks. They record the water activity and temperature-pressure conditions of their formation. The level of hydroxyl content can influence physical properties such as elasticity, rheology, and seismic behavior, and it provides important constraints on the geological history of a rock.

Detection and measurement: The presence and quantity of hydroxyl groups are typically assessed with infrared spectroscopy, which detects OH stretching vibrations near 3,600–3,700 cm−1, and complementary techniques such as Raman spectroscopy or secondary ion mass spectrometry (SIMS) for hydrogen content. Quantitative analyses may involve specialized calibration for water or hydroxyl in minerals.