Stone is a natural material that can be polished to a sheen so deep that it can actually look like a sheet of glass. After years of being walked on, stone will show wear and tear. When one waxes stone to create a barrier between it and foot traffic, yellowing and dullness may occur.

We recently watched while a cousin of ours used a broad-bladed putty knife to scrape a thick, yellow coat of wax off her terrazzo tile entry. It took about 10 minutes for her to do one square, but the yellow disappeared and the original shine was still there.

The spots might also be efflorescence. If scraping doesn't do the job, try scrubbing with a brass-bristle wire brush dipped in a concoction containing one part pool acid and 20-parts water.