what is a quartz heater? Is it more efficient than a ceramic heater?
I don't know if there's sandstone in the Philippines or not. But assumming there is no sandstone there, it could be because the area would be of mostly igneous and metamorphic rock. Where I live in New England, there is also very little sandstone except for two large areas, the Connecticut River Valley in parts of Massachusetts and Connecticut and the Aroostook Valley in northern Maine, there are a few smaller areas such as a part of Martha's Vinyard and a few other areas in eastern Mass. By and large, here it is almost all igneous and metamorphic rocks, the Phillipines might be similar
Sandstone by definition will have quartz in it. The particles in sandstone always contain quartz. Quartz is the most abundant mineral on earth. Is your teacher a geologist? Ask your teacher, if it not quartz then what is it? Let me know by email what they say (check my profile) and I'll tell you if they are correct or not.
The Philipines are composed of volcanic igneous rocks which are low in quartz. Any quartz that does weather out of the rock is transported in river beds and deposited on beaches where the action of current and waves prevents cementation of the sand.
