In the world of commercial stone, it’s common to group large numbers of stones with similar characteristics together under a single label. For example, gabbros and dolomites are frequently labeled as granites, because they share a lot of common minerals and patterns with true granite. This can get a little confusing if you’re looking for a specific stone that will hold up well in particular circumstances. One such confusion surrounds the group of stones known as “green marble”.
While there are a few types of calcium based marble that are also green – Cippolino and Verde Antigua – the vast majority of green stones that are called marbles, are actually serpentine. Serpentine is a group of minerals made of mostly magnesium silicate. Serpentines are usually green, but may vary in tone from nearly black to yellow, and may have some amount of white veining throughout their surface. Some studies carried out on green marbles used in architecture discovered that most of stones labeled as marble, but green in color contained 75 to 90% serpentine, with little or no calcite at all.
The benefit of using a serpentine is the fact that’s actually more durable than true marble. Serpentine is not reactive to acids, for example, which means that you can use one as a kitchen counter and not have to worry about etching.
On the other hand, however, serpentine does not react well in wet environments. The stone gets its name from the scaly pattern that often emerges on the surface of the stone. This is known as spalling, and can get worse when the stone absorbs moisture. Therefore, green marbles should always be installed using an epoxy-based setting material, and should either be sealed well or kept out of extremely wet area, such as steam showers, all together.
While most green marbles out there aren’t truly marble, they are still beautiful, durable stones that can enhance any area you install them in. Take care to install and care for them properly to help them last as long as possible.