Like name says, heavy mineral sand contains lots of heavy minerals. Density of these minerals is generally above 2.85 grams/cm³. Important heavy minerals are magnetite, garnet, ilmenite, zircon, spinel, augite, staurolite, hornblende, rutile, kyanite, tourmaline, biotite, titanite, apatite, etc.
These minerals appear often in sand but usually in low quantities (less than 1 percent). However, sometimes they are concentrated and form beautiful and unusual looking sands. There are many different looking heavy mineral sands but one which tends to appear most often contain garnet and magnetite as the key minerals. Most heavy mineral sands contain quartz also but it isn’t as important as usually.
The source material for heavy mineral sands are metamorphic and igneous rocks. Metamorphic rocks are source material for kyanite and garnet for example, although the latter may crystallise from magma as well. Magnetite is of igneous origin mostly.
Heavy mineral sands occur mostly in seashore or paleo seashore but also in some parts of streambeds. This sand type is natural mineral concentrate. Heavy mineral sand is not very rare but its area of occurrence is usually pretty limited.
Gallery of heavy mineral sands:
