Metaquartzite – Anglesey (1kg)
Metaquartzite specimens found in Anglesey, Specimens are supplied in a polythene bag in lots of 1 kg with a label.
Metaquartzite is a hard, non-foliated metamorphic rock which was originally pure quartz sandstone which was converted into quartzite through the heat and pressure usually associated with tectonic compression within orogenic belts. Pure quartzite is usually white to grey, though quartzites often occur in various shades of pink and red due to varying amounts of iron oxide (Fe2O3). Other colors, such as yellow, green, blue and orange, are due to other mineral impurities.
The original individual quartz grains recrystallize along with the former cementing material to form an interlocking mosaic of quartz crystals. Most or all of the original texture and sedimentary structures of the sandstone are erased by the metamorphism The grainy, sandpaper-like surface becomes glassy in appearance. Minor amounts of former cementing materials, iron oxide, silica, carbonate and clay, often migrate during recrystallization and metamorphosis. This causes streaks and lenses to form within the quartzite. These examples were collected near Holyhead on the Isle of Anglesey, North Wales. Specimens are supplied in a polythene bag in lots of 1 kg with a label.