 From 1871 to 1880 he was employed at copper mines in eastern Russia, and from 1882 to 1890 at the Lidjessi silver-lead mines in Asia Minor of which he was general manager from 1884.He went to Tasmania in 1890 and followed various occupations until August 1899, when he was appointed Tasmanian government geologist and chief inspector of mines.He was a joint author of a number of articles and books about western Tasmanian geology, including with William Frederick Petterd 

In 1914 the office of chief inspector of mines was made a separate one, but Twelvetrees continued to act as government geologist and director of the geological survey of Tasmania until his death.