Abstract
Our attention is paid to ophiolite as analogous geological environment to the generation process of hyperalkaline leachates from cement. The field survey of the natural analogue was carried out in northwestern Luzon in the Philippines where bentonite is close to ophiolite. Then we analyzed the mineralogical properties of bentonite by XRD, FESEM-EDX, EPMA and Polarization Microscope. The results showed that bentonite had formed alteration zone, but the zone was small.