Tantalum
Tantalum (Ta) is a lustrous, dark grey metal that is one of the Refractory metals, a group of metallic elements that are highly resistant to heat and wear and highly corrosion-resistant.
Tantalum was discovered in 1802 by Anders Ekeberg who named it after Tantalus (a figure in Greek mythology) because of what he saw as the tantalizing problem of the inability to dissolve the oxide in acids. Tantalum always occurs in geologic sources together with the chemically similar niobium, which was named after one of the children of Tantalus: Niobe, the goddess of tears.
Tantalum, although difficult to work with, has such a rich deep colour which contrasts beautifully with gold and silver. Phoebe exploits this colour contrast to great effect in her stacking and interlocking rings. Tantalum's dark colour is not a surface treatment and therefore will not wear off or change with time, unlike many other dark finishes.
Tantalum cannot be soldered, so it can't be fabricated using traditional jewellery techniques. It must be forged, cut or cold joined, presenting challenging design constraints that lead Phoebe to innovative approaches to jewellery making. Finally, tantalum is relatively dense, with a specific gravity of 16.6 gm/cc similar to 18ct gold. What this means in practice is that tantalum feels heavy for its volume like gold (and unlike aluminium or titanium) making it feel very substantial - a great property for rings, but not so suitable for earrings and necklaces which are usually easier to wear the lighter they are.
