The soils in which I work are an extraordinary blend of different components, but long experience is necessary if one is to coax high-quality wines from them.
The main component, without doubt, is a very dense, compact white clay, the main reason that cultivation of San Miniato vineyards is so laborious.
But the other geological strata that go to make up these soils are as various as one could imagine, composed mainly of a whole series of sandstones and Pliocene-era marine fossils, and the layers are quite thin.
One encounters therefore shells of every size and in such quantities that in some areas they themselves make up the predominant texture of the soil, as well as sands ranging in granulosity from very fine to coarse and heavy, layered in various configurations and varying increasingly in minerality and fertility the deeper one goes.
To obtain the best results from the vineyards the vines need some years to push their roots deep to access the most complex mix of nutrients.