What is platinum?

When you mention jewelry, images of silver, gold, and platinum probably come to mind. Did you know that platinum is ranked among precious metals due to its rarity and high economic value? Explore with us what platinum represents.

DISCOVERY OF PLATINUM

Platinum, a precious metal prized in the creation of jewelry, carries with it a rich and centuries-old history.

Its use dates back to ancient Egypt, around 700 BC, where modest quantities were employed. Traces of platinum were identified on a coffin discovered in the tomb of Queen Shapenapit in Thebes. Unlike other civilizations such as Greece, Rome or China, platinum was not noted in their respective cultural contexts.

Yet, on the other side of the globe, in South America, between Colombia and Ecuador, funerary objects containing platinum, about 2000 years old, have been unearthed. This discovery constitutes captivating evidence of the use of platinum across different regions of the world throughout history.

A PLATINUM SAMPLE

Given that the origin of the discovery of platinum remains unknown, the real question lies in who discerned the uniqueness of this metal and when it happened. An Italian scientist named Julius Scaliger seems to have been the pioneer in this matter. In 1557, he wrote about a metal originating from Central America that did not melt, thus attributing to it the name of platinum. Unfortunately, Scaliger went largely unnoticed, and platinum was rediscovered later.

In the 18th century, the Spaniards, after conquering South America, looked into a strange metal that showed similarities with silver while retaining its shine. In 1735, Antonio Ulloa studied platinum in Panama and shared his findings with the Royal Society of London. It was at this time that the recognition of platinum as a unique metal and element took shape in people's minds.

PLATINUM, IN PRACTICE...

Among metals, platinum stands out as one of the least reactive. Its remarkable resistance to corrosion, even at high temperatures, makes it a major metallic element. Generally found in its native state, platinum is encountered uncombined chemically, mainly in certain nickel and copper ores, as well as in native deposits, with South Africa contributing to 80% of global production. The alluvial sands of various rivers naturally contain platinum, and the pre-Columbian indigenous populations of South America were the first to use it in the manufacture of handicrafts.

Platinum finds varied applications, notably in catalytic converters, laboratory equipment, electrical contacts and electrodes, platinum resistance thermometers, dentistry instruments, and jewelry. Although exposure to platinum salts can pose health problems, metallic platinum, due to its resistance to corrosion, is not associated with adverse health effects. Furthermore, compounds containing platinum, such as cisplatin, oxaliplatin, and carboplatin, are used in chemotherapy to treat certain types of cancers.

HISTORY OF PLATINUM

Archaeologists have identified traces of platinum in the gold used during burials in ancient Egypt, dating back to 1200 BC. The pre-Columbian Americans, near present-day Esmeraldas in Ecuador, also exploited this metal to make objects from an alloy of white gold and platinum. They implemented the sintering process by combining gold and platinum powders. The resulting alloy was malleable enough to be shaped with tools. It is important to note that the platinum used in these objects was not in its pure form, but was a mixture containing small amounts of rhodium, palladium, and iridium.

The first mention of platinum in European culture appears in the writings of the Italian humanist Julius Caesar Scaliger in 1557. These writings mention an unknown metallic element discovered between Darien and Mexico, "which no fire or Spanish artifice has yet been able to liquefy." Antonio de Ulloa is recognized as the discoverer of platinum in European history. In 1748, Antonio de Ulloa established the first mineralogy laboratory in Spain and was the first to undertake a systematic study of platinum. In 1752, Henrik Scheffer named it "white gold".

FEATURES OF PLATINUM

PHYSICAL CHARACTERISTICS

Pure platinum presents itself as a brilliant, ductile and malleable metal.
Displaying a silvery white hue, platinum demonstrates a ductility superior to that of silver, gold or copper, thus classifying it as the most ductile pure metal.
Thanks to its resistance to corrosion, its stability at high temperature and its stable electrical properties, platinum stands out.
At a temperature of 500 °C, platinum oxidizes; however, this oxide is generally easily removed by thermal means.
An energetic reaction occurs with fluorine at 500 °C, leading to the formation of platinum tetrafluoride.
Platinum also undergoes an attack from chlorine, bromine, iodine and sulfur.
Insoluble in hydrochloric acid and in aqua fortis (strong water), platinum however dissolves in hot nitro-hydrochloric acid.

CHEMICAL CHARACTERISTICS

The most common oxidation states of platinum are +2 and +4.
The +1 and +3 oxidation states are less frequently observed.
Although elemental platinum generally exhibits low reactivity, it dissolves in hot nitro-hydrochloric acid, yielding aqueous chloroplatinic acid.
Platinum behaves like a mild acid and has a strong affinity with sulfur, especially in compounds such as dimethyl sulfoxide.

PLATINUM PRODUCTION

Platinum, along with other platinum group metals, is commonly obtained as by-products of nickel and copper mining and processing. During the electro-refining process of copper, noble metals such as silver, gold, and those of the platinum group settle at the bottom of the cell in the form of "anode sludge", serving as a starting point for the further extraction of platinum group metals.

When pure platinum is discovered in alluvial deposits or other ores, it is isolated using various methods aimed at removing impurities. Due to its significantly higher density than many impurities, lighter elements are often removed by allowing them to float in a liquid. Heavier nickel and iron impurities are removed using an electromagnet. Since the melting point of platinum is higher than that of most other substances, many impurities are burned or melted without affecting the platinum. Finally, platinum, resistant to hydrochloric and sulfuric acids, remains unscathed, while other substances are attacked by these acids. Metallic impurities are often removed by stirring the mixture in one of these acids, thus allowing the remaining platinum to be recovered.

An effective method for purifying raw platinum, containing platinum, gold, and other platinum group metals, is to treat it with nitro-hydrochloric acid. In this process, platinum, palladium, and gold dissolve, while osmium, iridium, ruthenium, and rhodium do not react.

PLATINUM APPLICATIONS

Catalyst: Platinum plays a predominant role as a catalyst in various chemical reactions, a use that dates back to the early 19th century. Since then, platinum powder has been used to catalyze the ignition of hydrogen. It plays a crucial role in the oil industry by catalyzing the reforming of naphthas, thus directly transforming distillation into higher octane gasoline, enriched with aromatic compounds. Its most essential application lies in automotive converters, promoting the complete combustion of unburned hydrocarbons present in exhausts, transforming them into water vapor.
Investment: Platinum, a precious and opulent raw material, finds its utility in the field of jewelry, often in the form of a 90-95% alloy, taking advantage of its inertia. It is also prized for its prestige and intrinsic value as a precious metal. In watchmaking, renowned companies such as Rolex, Patek Philippe and Breitling use platinum for the production of limited edition watch series, thus adding a luxurious dimension.
Standard: Between 1889 and 1960, the meter was defined by the length of a platinum-iridium alloy bar (90:10), known as the international prototype of the meter. The platinum resistance thermometer (SPRT) is one of the four types of thermometers used to define the International Temperature Scale of 1990 (ITS-90), the international calibration standard for temperature measurements. The resistance wire inside this thermometer is made of pure platinum.
Other uses: Platinum also serves as an alloying agent in the manufacture of various metal products such as fine wires, non-corrosive laboratory containers, medical instruments, dental prostheses, electrical contacts and thermocouples. The platinum-cobalt alloy, composed of about three parts platinum and one part cobalt, is used to create relatively powerful permanent magnets. Platinum-based anodes are visible in various applications, from ships to pipelines to steel piers.

QUESTIONS / ANSWERS ABOUT PLATINUM

Q.1. HOW CAN I KNOW IF MY RING IS MADE OF REAL PLATINUM?

Answer: All platinum jewelry comes with a mark guaranteeing its authenticity. You just need to look for the terms "Platinum", "PLAT" or "PT", possibly preceded by the numbers "950" or "999". These numbers refer to the purity of the platinum, with "999" being the highest degree of purity.

Q.2. DOES PLATINUM STICK TO A MAGNET?

Answer : Gold, silver, and platinum do not exhibit magnetic properties. It is important to note that the presence of a magnetic attraction indicates a mixture of alloys rather than a pure precious metal.

Q.3. DOES PLATINUM WEAR OUT?

Answer : Platinum has exceptional durability. Unlike other precious metals that lose metal and wear out faster when scratched, platinum has a significantly slower wear rate.