Summary: Several types of microscope-mounted drills have been described in literature to obtain pure mineral material from thin sections or polished sections (e.g. Granigg, 1915; Moritz, 1929; Haycock, 1931; Russanow, 1937; Machairas, 1967), but all of them appear to be of limited mechanical stability and reliability. This paper describes an improved drill to extract under the microscope minute quantities of pure material from thin or polished sections. The drilling is performed in a liquid (silicon-oil) to minimize loss of the drilled-out mineral powder. With the help of a micromanipulator the liquid, together with the borings, is drawn up into a microcapillary tube (less than 30 µm in diameter) made of Lindemann glass. For identification of the mineral powder the microcapillary is mounted in a Debye-Scherrer X-ray diffraction camera.