Intrusive igneous rock from Quadeville, Ontario.
Pegmatites are rocks with minerals that are greater than oneÌýcm in size. AsÌýmagma cools, small crystals of common minerals begin to form. This produces a higher concentration of rarer elements such as lithium and berylliumÌýin the remaining melt. This highly concentratedÌýmaterial isÌýthen injected into the surrounding rock, such as through a fracture system. The melt cools rapidly, with large growth rates creatingÌýhuge crystals of quartz, feldspar and mica. RarerÌýberylÌýand tourmaline form attractive crystals if there is sufficient space for them to grow.
The Quadeville pegmatites were worked before the second world-war (WW2) for beryl crystals. The ore was shipped to Germany before WW2Ìýand used to make armoured steel for military use. Some roseÌýquartz can be cut into cabochon stones showing asterism (a star-pattern). This pattern is caused by tiny rutile crystals (titanium oxide) in the rose quartz.
