Niobium is in the minerals columbite and pyrochlore. Mixtures of columbite and tantalite are called coltan. Tapiolite is very close to "columbite" and "tantalite". By the 1940s, Nigeria was a major producer of tin, columbite, and coal. Associated minerals include zircon, aegirine, apatite, perovskite and columbite. The iron-rich member of the columbite group is ferrocolumbite. Associated minerals include quartz, feldspar, spodumene, amblygonite, tourmaline, columbite, cassiterite, topaz and beryl. Over time, the mine would produce quantities of quartz, feldspar, mica, beryl, spodumene and columbite. Columbite and tantalite are collectively known as coltan in Africa. This confirmed that Charles Hatchett had discovered niobium in 1801 in columbite ore. Uranium and thorium were in the monazite grains; rare earths were in columbite and euxenite. In 1801, Hatchett analyzed a piece of columbite from the collection at the British Museum. The area's economic activity centers on the tin and columbite mining industry and farming. Columbite and tantalite are ores used to produce the elements niobium and tantalum. However, tantalite has a much greater specific gravity than columbite (8.0+ compared to columbite's 5.2).