Hematite: the black diamond

Varieties of hematite can range in colour significantly from black to steel or silver-gray, brown to reddish brown or red. Irrespective of shade, the different forms share a rusty red streak that is somewhat responsible for the name of the mineral: Hematite takes its name from the Greek root prefix ‘haema’, meaning blood, its colour when powdered. 

Found in England, Mexico, Brazil, Australia and the Lake Superior region of the United States and Canada, Hematite occurs in varying states of compactness. While most hematite is suitable as an ore for smelting, it is the most compact form – a deep blue-black colour – that is cut into jewellery. This type, often known as black diamond, can be created through aqueous or weather processes and is located in large masses made up of radially fibrous crystals. These masses are known as kidney ore because of their shape and their hardness can be as high as 6.5 on Moh’s scale. 

 

Hematite is linked to the presence of water and, while water is not essential to its formation, it is often found in spots that have been the location of standing water bodies such as lakes and springs. The mineral can precipitate out of water and collect in layers at the bottom of a lake, spring, or other standing water. 

It is this fact that excited NASA scientists when they found small samples of hematite during a mission to Mars in 2004. The samples are believed to have formed as rock deposits under watery conditions billions of years ago when Mars had water. 

Early uses of hematite revolved around its softer form, which occurs as a red ore. The mineral’s colour and the ease with which it could be powdered made it ideal as a paint pigment or as a rouge for cosmetics. Most famously, American Indians used hematite to make the paint that marked them in battle.

The history of hematite’s healing properties is extensive. As far back as ancient Egypt, hematite was used to reduce inflammation and treat hysteria. In addition, hematite was used to treat tumours and blood diseases when mixed with egg and oil respectively. 

Fascinatingly, however, the virtues of hematite were praised in an ancient text written by Azchalias of Babylon for Mithridates the Great, King of Pontus (d. 63 B.C.), a sovereign who possessed a vast collection of stones. Azchlias asserted that hematite talismans procured fortune and favouratism for the wearer, especially with legal issues. 

When set in jewellery, hematite is most often cut as a round brilliant gem, at least as far as the crown is concerned. Often the underside of the stone is left unpolished and flat. This use of the brilliant cut can fool some into mistaking it for black diamond, especially given its deep luster and shiny smooth appearance. There have been examples of the gem produced as a bead and used to imitate black pearl also.