In 1800, English scientist William Hyde Wollaston stumbled upon a rare and unknown metal while experimenting with platinum ore, leading to the discovery of rhodium, the Earth’s scarcest and costliest precious metal.
Rhodium, symbolized as Rh and with atomic number 45, is a shiny, corrosion-resistant element extensively used in various industries, including automotive, jewelry, and chemical sectors. Its scarcity and high demand, especially in the automobile industry for emission control, contribute to its exorbitant value, currently priced at $14,000 per ounce.
Unlike other metals, rhodium is typically a byproduct of platinum, copper, and nickel refining processes. South Africa remains the largest producer of rhodium through its substantial platinum mining activities, with minor deposits found in North and South America and Canada.
Named after the Greek word for rose due to its reddish salts, rhodium belongs to the platinum metals group, characterized by allure, workability, durability, and rarity. Other members of this group include platinum, palladium, ruthenium, iridium, and osmium.
Although rhodium is generally not harmful to humans due to limited exposure opportunities, precautions are necessary during jewelry-making processes to avoid inhaling potentially dangerous fumes. Rhodium plays a crucial role in catalytic converters, reducing harmful emissions from vehicles and aiding in various chemical reactions.
Its exceptional properties, such as resistance to corrosion and high electrical conductivity, make rhodium an ideal coating for optical fibers, mirrors, and electrical components. Jewelry makers favor rhodium plating for its bright, silvery appearance, hardness, and hypoallergenic nature, ensuring durability and wearability.
Despite its desirability, rhodium’s high melting point and hardness pose challenges for jewelers, necessitating thin plating that may wear off over time. Replating jewelry every one to two years is recommended to maintain its luster and appearance.
Thanks to Wollaston’s groundbreaking discovery over two centuries ago, rhodium continues to hold its status as one of the most precious and valuable metals on Earth, enriching industries and enhancing everyday products like jewelry and automotive components.