External (in-air) Particle Induced Gamma-ray Emission (PIGE) setup of FOlded Tandem Ion Accelerator (FOTIA), Bhabha Atomic Research Centre (BARC) was utilized for determining concentrations of low Z elements (Si, Na, Al and F) in geological samples by a simple and novel sample preparation method using thin Mylar films to pack direct solid samples. Low energy proton beam was utilized and the current-normalized count rates of analytes were obtained using the count rate of tantalum, the beam exit window material. Meticulousness of the method was ascertained by analysing different CRMs and compared with conventional pelletisation method. Proposed method was adopted for elemental analysis in uranium ore samples for possible nuclear forensic applications.