Tantalum is a chemical element with the symbol Ta and atomic number 73. It is a very hard, ductile, lustrous, blue-gray transition metal that is highly corrosion-resistant. Tantalum is part of the refractory metals group, which are widely used as components of strong high-melting-point alloys. It is sometimes found uncombined in nature, but mainly occurs in the mineral columbite-tantalite, which also contains other metals including niobium. Tantalum is mined in many places including Australia, Canada, and Brazil. It is obtained commercially as a by-product of tin extraction. Tantalum is used in a variety of alloys to add high strength, ductility, and a high melting point. It is also used in tantalum capacitors for electronic equipment such as computers. Tantalum is being investigated for use as a material for high-quality superconducting resonators in quantum processors. Tantalum is considered a technology-critical element by the European Commission. Tantalum is a hypoallergenic metal and is extremely crack-resistant. It is used in making surgical instruments and implants.