This is powerful protective mantra of Dorje Gotrab aka Padma Shawari (so called "Vajra Armour") written traditionally by gold on the dark-blue paper. Tibetans seal such mantras in the scroll, put in the gao and wear on the neck against infection diseases and cancer.
Common pronunciation of this mantra is below:
OM PADMA SHAVARI PHAT / NÄN PAR SHIG / NAGA NÄN / TADYATHA / SARVA / BRITA / HANA HANA / VAJRA NA / RAKSHA RAKSHA / SVAHA//
ཨོམ་པདྨ་ཤ་བ་རི་ཕཊ༔ ནན་པར་ཤིག༔ ནཱ་ག་ནན༔ ཏདྱཐཱ༔ སརྦ་ཝི་རི་ཏ༔ ཧ་ན་ཧ་ན་བཛྲེ་ན་རཀྴ་རཀྴ་སྭཱཧཱ༔
The diameter of the scrolled mantra is 6.0 mm approx.