Several minerals are found in hyaloclastite masses. Sideromelane is a basalt glass rapidly quenched in water. It is transparent and pure, lacking the iron oxide crystals dispersed in the more commonly occurring tachylite. Fragments of these glasses are usually surrounded by a yellow waxy layer of palagonite, formed by reaction of sideromelane with water.
Hyaloclastite ridges, formed by subglacial eruptions during the Ice age, are a prominent landscape feature of Iceland and British Columbia. Hyaloclastite is usually found at subglacial volcanoes, such as tuyas, which is type of distinctive, flat-topped, steep-sided volcano formed when lava erupts through a thick glacier or ice sheet.
Mechanisms of slope failure on Pyramid Mountain, a subglacial volcano in Wells Gray Provincial Park, British Columbia.
Feb 01, 2006; Abstract: Pyramid Mountain is a subglacial volcano in Wells Gray Provincial Park in east-central British Columbia. Landslides...