Charles Hatchett's work on chemistry occurred mostly between 1796 and 1806, a ten-year period. In 1796, he published "An analysis of the Corinthian molybdate of lead", resolving a dispute over the nature of the mineral.  In 1797 he was elected a Fellow of The Royal Society, largely as a result of this work. In more than 20 additional papers, he addressed the chemistry of minerals, resins and natural products.
In 1800 Hatchett may have opened a small chemical works at Chiswick in London.
In 1798, Hatchett was asked by members of the Privy Council to work with Henry Cavendish and assess "the state of the coins of the realm" to ensure that they were not being adulterated. 
He produced a 152-page-long report in 1803. He concluded that there was no important defect in the composition or quantity of the standard gold.
Hatchett developed a collection of over 7000 minerals, which he sold to the British Museum in London in 1799. He agreed to organize the museum's mineral collection, but retained the right to remove and analyze portions of some of the specimens.
In 1801, Hatchett analyzed a piece of columbite from the collection at the British Museum. Columbite turned out to be a very complex mineral, and Hachett discovered that it contained a "new earth" which implied the existence of a new element. Lavoisier had defined the term "element" a mere 13 years previously.  Hatchett called this new element "columbium" (Cb) in honour of Christopher Columbus, the discoverer of America.
On 26 November of that year he announced his discovery before the Royal Society.
In 1802 Anders Gustaf Ekeberg (1767–1813) announced the discovery of another new element, "tantalum". For many years, there was confusion over whether columbium and tantalum were the same. 
In 1846, German chemist Heinrich Rose argued that there were two additional elements in tantalite, which he named niobium and pelopium for the children of the Cyclops. Eventually, Roses niobium (atomic number 41) was found to be identical to Hatchetts columbium. In 1949, the name niobium was chosen for element 41 at the 15th Conference of the Union of Chemistry in Amsterdam.