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Ytt′ro-cē′rite, a violet mineral found embedded in quartz, a fluoride of yttrium, cerium, and calcium; Ytt′ro-col′umbite, -tan′talite, a brownish mineral found at Ytterby, a tantalate of yttrium, uranium, and iron, with calcium.

Without planeloads of mica, quartz crystals, tantalate, columbite, industrial diamonds and rare drugs, the production lines of magnetos, electrical apparatus, stainless steel and medicines would have stopped dead.

They are probably present in the form of columbite, a niobate of iron and manganese; and tantalite, a tantalate of the same metals.