Only a few metals are required to produce a wide array of durable labware. The basic noble metals group consists of platinum, rhodium, ruthenium, osmium, palladium, iridium, gold and silver. Ruthenium and osmium, however, are unworkable in their pure form, and are only offered under special circumstances.

Platinum

Platinum is the best known and least rare of the platinum group metals. Its high melting point, 1773 °C, ductility and excellent resistance to chemical attack by acids and fusion mixtures makes it very suitable for laboratory ware.

Platinum - Gold

Platinum 5% gold is commonly used in sample preparations of glass beads for X-ray fluorescence analysis in the glass, cement and ceramic industries. Universally accepted material of choice for crucible and casting moulds for spectrographic analysis by x-ray fluorescence (XRF). The alloy has higher temperature strength than pure platinum and has a “non-wetting” property, which results in easy removal of the sample after fusion and allows for many reproducible assays.

Platinum – Rhodium

When physical conditions require high labware strength at all temperatures, a platinum 10% rhodium alloy offers superior performance to pure platinum. This alloy has melting point of 1850 °C, it has greater hardness and higher strength than other platinum alloy. It is capable of maintaining its shape under the hottest furnace conditions. It is not recommended for applications that involve repeated fusions, since it is slightly more susceptible to chemical attack than pure platinum. The rhodium alloys have higher hardness and high temperature strength making it suitable for more aggressive conditions.

Gold

Gold is sometimes used for hydrofluoric acid treatment of siliceous materials.

Iridium

Pure iridium crucibles are widely used for the growing of crystals from high-purity melts at temperatures of up to 2200°C. Further details on iridium crucibles are available upon request.