Off white-speckled? That would be usually lichen, leave them alone. Birds pick them off to make their nests. The stones are usually polished Niagara limestone or similiar to it. White marble - take extreme care while clean with only water. Anything else will cause wear off because these types of marble are soft. Gray granite is not necessary smooth. They're not intended to be polished, comes from Vermont granite. Can be difficult to clean with pressured water. Use nylon brush Polished quartz are in vogue from 1940s onwards. Chipped quartz are usually blue or red. Red is worst when it come to cleaning and photographing. Lately, seen in current active cemeteries - black "lacquered" marble from China. This solution from France has interesting method http://www.valmour.fr/advices/gravestone-maintenance,121 David Samuelsen On 5/3/2012 1:56 PM, Gale Gorman wrote: > I knew that was coming. They vary. Some are granite and resemble a more recent monument even though the date is c.1910. Some are the off-white stone tall in shape and difficult to read unless the light is just right to create shadows of the letters. > > The gray granite markers mostly have a mossy mildewed appearance. The off-white markers are speckled with no telling what. > > Then there is one in Arkansas that is probably granite but not faced off as smooth as most markers. > > Gale Gorman > Houston > > > On May 3, 2012, at 2:14 PM, W David Samuelsen wrote: > > what kind of stones are they? Cleaning is not same for every stone. > Most requires only water. > > David Samuelsen > > On 5/3/2012 12:33 PM, Gale Gorman wrote: >> >> On May 3, 2012, at 1:13 PM, Kathie Harrison wrote: >> >> Tom, I started that list and it was hugely subscribed to and I ran it >> for the first couple years and had alot of bickering on it with the >> pros and cons of cleaning tombstones... >> -----------snip---------- >> >> I have a few grave markers I need to visit and clean. What's the best method or solution? >> >> Gale Gorman >> Houston >> >