Travertine and all stone of that class can stand injury whether from a heavy load laid upon it or from the weather; exposure to fire, however, it can… - Vitruvius

If there are no sandpits from which it can be dug, then we must sift it out from river beds or from gravel or even from the sea beach. This kind however has these defects when used in masonry: it dries slowly... and such a wall cannot carry vaultings. Furthermore, when sea-sand is used in walls and these are coated with stucco, a salty efflorescence is given out which spoils the surface.

Fresh pitsand, however, in spite of all its excellence in concrete structures, is not equally useful in stucco, the richness of which, when the lime and straw are mixed with such sand, will cause it to crack as it dries on account of the great strength of the mixture. But river sand, though useless in "signinum" on account of its thinness, becomes perfectly solid in stucco when thoroughly worked by means of polishing instruments.

Burn shavings and splinters of pitch pine, and when they turn to charcoal, put them out, and pound them into mortar with size. This will make a pretty black for fresco painting.