Black Steel Stone
This stone is also called ‘marcasite stone’ or’ Africa black gold’. It is a steel-white iron sulphide mineral used for jewellery. It can be composed of haematite, goethite, or both. It contains 6–7% silica and has a Mohs hardness of 6.5, a specific gravity of 4.67–4.87 and a refractive index of 2.26–2.39. It has a unique non-fading lustre and is often used in various types of jewellery. It has remarkable decoration effects. Marcasite jewellery originated in the Victorian era (mid-eighteenth century) and was crafted by royal craftsmen. Only the royal family was allowed to wear this jewellery. In the late eighteenth century, this type of jewellery began to be produced outside the royal family and spread across Europe and then throughout the world in the nineteenth century.