Metaquartzite – Norway
Metaquartzite specimens from Lom, Central Norway. Typical hard white masses of crystalline metaquartzite. Specimens are supplied in a card tray 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. This example comes from Lom in central Norway. Specimens are supplied in a labelled card tray.