Magnetite is a ferrimagnetic mineral known under the chemical name ferrous-feric oxide, having chemical formula Fe3O4. Magnetite is the most magnetic naturally occurring mineral on Earth being known since the ancient times. Magnetite is often found in beach sands with igneous and metamorphic origins.
The sample above comes from Bali island, Indonesia (sample no. 1005 in my Sand Atlas). When taking the photo I noticed some yellow-brown-kaki translucent grains (they were not visible with naked eye). I was just curious to know whether I can somehow sort out the “foreign” grains (presumably olivine).
Using a magnet the result was great: indeed, only some of the particles (about 2/3 from total volume) have been attracted by the magnet, the rest remaining still. I also noticed that not all dark particles were gone, some were ignoring the magnetic force, so that not everything was magnetite.
