Niobium is chemically very similar to tantalum and it is very difficult to separate them, hence the name niobium. The element was named after Niobe, daughter of Tantalus, of Greek mythology. Tantalum was named, of course, after Tantalus. Niobium is a very unreactive metal and insoluble in acids, even in aqua regia. Some people who prefer metals harder than gold or platinum but are allergic to nickel, etc., choose niobium rings for their wedding rings. Although the metal and oxides have virtually no solution chemistry, tetrabutylammonium salts of polyniobates are very soluble in water and polar organic solvents.
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