Before you get queasy, a little history:
People have known about Carrara's white marble since Pre-Roman times, and have been extracting it since they discovered it. In the days before mechanized transportation most people went on foot, so having the town as close to the workplace as possible was important, and the Roman quarrymen (for the most part slaves) founded Colonnata on a ridge between two quarries. Steep forested hills where they could gather chestnuts, acorns, and such, but not much in the way of arable land, nor a place where one could easily raise goats, sheep, or cattle.
But pigs do very well with acorns and chestnuts, so every family had at least one, which they would butcher in the winter. The meat, of course, got eaten, but pigs also have lots of lard, and the townspeople discovered they could cure it in their cellars if they put it in marble tubs, covering it with salt and herbs (garlic, rosemary, peppercorns, anise, and other things): The salt draws the water out of the fat, forming a brine, and in its dehydrated state the fat is much more receptive to the oils in the herbs, which flow into it and flavor it over a period of several months.
The production technique guaranties a safe food because the salt ties up all the water, making it impossible for any form of bacteria to grow, the herbs and spices make it amazingly delicate and flavorful, and the calories make it perfect for the men to take into the quarries. People were already writing admiringly of it in the mid-1800s, and since then its renown has grown tremendously.
Should you buy some Lardo di Colonnata, what to do with it? Slice it very thinly and serve it on warm slices of toasted bread as an antipasto. There are other fancier pates and spreads, but I find this to be the most satisfying use. Or use it in the kitchen: Finely sliced, and tied over a drier meat, for example pheasant or turkey breast, or even a lean boned pork loin. Saves basting and adds a delightful touch.
More about Lardo di Colonnata
A general overview of salumi, Italian cold cuts.
Affettati Misti, a mixed cold cut antipasto