At Sungloss Marble Restoration Company, we have been repairing, cleaning, refinishing, polishing and honing marble, limestone, granite, terrazzo, slate, and many other stone surfaces for over 20 years. But we almost never stop to think about where it all starts—the origin of the beautiful, versatile, and natural material known as marble.
In basic terms, marble originates from limestone. So, what is limestone? Limestone is a sedimentary rock, formed from deposits of mineral specks, sand, and dead organic matter (mollusks, coral, etc). After many years of one layer slowly covering another layer, the stone forms sometimes in sheets, and sometimes minerals will precipitate in a more uniform manner. The primary mineral component of limestone is calcite (calcium carbonate).
When limestone continues to be subjected to heat and pressure over additional years, the stone undergoes a metamorphosis. Hence the classification of marble as a ‘metamorphic’ rock . Marble still is composed of mainly calcite, but the organic specks, sand, and general visual characteristics that define limestone are transformed into a smooth, tight grain. The metamorphosis causes a complete recrystallization of the limestone. Marble’s veins come from impurities and natural striation in the father limestone. Pure white marble comes from high calcite, pure limestone.
The main characteristic that concerns us when understanding marble’s chemical makeup is calcite’s natural reaction to acid. Due to the author’s barely passing grade in chemistry class, all we can tell you is acid will etch calciferous stone, releasing carbin dioxide bubbles (it has to do with the way carbon is chained together in the calcite…for more reading, see this chemistry lesson on calcite). The etched surface looks different than the adjacent stone, and can be an eyesore if the marble is polished. Another characteristic is the stone’s natural hardness. In the geologic world, the MOHS scale is used to compare different stone and mineral’s hardness. On the 0-10 scale, marble comes in between 2 and 5. What that indicates is, marble is truly not a hardy material compared to other minerals, stones, and metal objects. The Marble Institue of America states the first eight steps into your home track particles into the house. That means a marble floor will have bits of sand and dirt ground into it for those eight steps, and there’s a high probability the particles are higher on the MOHS scale than the marble itself. What happens when a harder material is ground into the softer marble underneath? It scratches, of course. Fine scratches over time will dull the surface, while deep scratches are noticable eyesores.
That’s where Sungloss Marble Restoration comes in to the picture. Whether they know about the actual chemistry or geology, I can guarantee our commercial clients’ looking to maintain their lobbies, construction companies with post-job cleanups, and residential customers looking to spruce up their beautiful (and expensive) investment all know about etches and scratches! Those two blights are a substantial portion of how we got into this business, and how we continously add value to our clients’ marble by naturally correcting the problems through environmentally-concious methods. Ultimately, we cannot escape the inherent properties of the natural wonder that we all know as marble—but we can maintain it as best we know how, to preserve marble’s beauty, along with our water and air for future generations.