Oxygen is extracted from silicate and oxide minerals by the laser fluorination technique (Valley et al., 1995). Pure mineral separates (2-3 mg) are loaded on a pitted stainless steel holder, and placed in BrF5 atmosphere in a stainless steel reaction chamber. Oxygen is qualitatively liberated from the minerals by reaction with BrF5 during focused heating by New Wave MIR-50 laser. Reaction is monitored through a CCD video camera and remotely controlled by a laser navigation system and software. Oxygen is purified cryogenically and with an inline hot KCl trap, converted to CO2 using a hot graphite rod, and analyzed on a Delta V isotope ratio mass spectrometer.