1. Platinum is a metal with the atomic number 78, which means it has 78 protons around its nucleus.
2. On the periodic table, it is abbreviated to "Pt".
3. Because of its silvery-grey colour, when Spaniards in South America first saw platinum in the 1700s it was called plata – Spanish for silver.
4. The platinum group of metals includes ruthenium, rhodium, palladium, osmium and iridium. Platinum and palladium are found in pure form; the rest are found in alloy with gold, or with platinum itself.
5. Platinum is used as a catalyst in the production of various acids, chemicals and pharmaceuticals. It is a key part of devices to reduce car and industrial emissions. Other platinum-group metals are used in electrical contacts or resistors, as well as in dental work and jewellery.
6. South Africa and Russia mine almost all the world's platinum. South Africa has about two-thirds of the total.
7. The mines of Lonmin, at whose Marikana site police shot dead 34 protesting strikers on August 16, comprise 12% of global supply. Marikana accounts for more than 90% of Lonmin's platinum output. Lonmin is the world's third-largest platinum producer after Anglo Platinum and Impala. Lonmin shares fell by 5% in London and 4% in Johannesburg after the killings.
8. This week, Royal Bafokeng Platinum announced that its output for 2012 had fallen and that it had suffered a 60% drop in earnings.
9. Platinum was selling at about $1457 an ounce this week, up from about $1400. Its highest price was $1 900 an ounce. Prices have dropped over the past year as demand from car-makers fell. After the Marikana slaying, prices of platinum futures went up.
10. A plain platinum wedding ring sells in the United States for about $1 900. The equivalent in 18-carat gold is about $680.