Know Your Stone

Know Your Stone

December 07, 2016


Calacatta Original for blog.jpg

Calacatta Original Marble

Here at Marble and Granite, Inc. our mission is to provide the very best materials from around the world. We want each and every slab that comes through our doors to become part of a project that the end user loves. And we want it to last. We believe that one of the most important things we can do, besides offer unparalleled quality and service to the designers, architects, fabricators, and homeowners we work with, is to educate. Quite simply, if you know your stone, you can care for it properly.

If the end user understands the surface, and its various properties, they are better equipped to care for it and help ensure that the surface lasts a very long time. We also believe that in order to make the best selection for a project, it’s very important that those involved in the planning process get to know the stone as well as possible too.

One of the best ways to get to know your stone is to understand its geological classification and composition. This helps you figure out which cleaning products to use and which cleaning methods will work best for your countertops, flooring, walls, fireplace surrounds, vanities, or any other area where you might incorporate natural stone.

Natural stone is classified into three basic categories, depending on how they are formed.

Sedimentary- Many layers, compressed together over time. Examples of sedimentary rocks include limestone, shale, coal, amber, and sandstone.

Igneous- Made when magma solidifies. Granite, basalt, pumice, and obsidian are types of igneous rock

Metamorphic- Created when sedimentary, igneous and pre-existing metamorphic rock are changed by heat, pressure, and chemically reactive waters. Examples of metamorphic rocks include schist, slate, gneiss, quartzite, and anthracite coal. Marble is also a metamorphic rock, formed from limestone.

Rocks in these three categories can be broken down further into two categories:

Calcareous stone is made mainly of calcium carbonate, a chemical compound commonly found in natural stone, shells, and pearls. It’s sensitive to acidic substances and usually requires different cleaning methods than siliceous stone. Examples include marble, travertine, limestone, and onyx.

Siliceous stone is made of silicates like quartz, feldspar, mica, etc. It is usually resistant to most acids found in the kitchen or bath. However, they can contain trace levels of minerals that are acid sensitive. It tends to be very durable and relatively easy to clean. Types of siliceous stone include granite, slate, sandstone, quartzite, brownstone, and bluestone.

Understanding which type you have can be very useful. While it’s not vital for you to know the chemistry behind it (there won’t be a quiz later), it is helpful to understand whether a stone etches, scratches, or stains, in addition it will be helpful when deciding which cleaning products to use on your stone.

So, how do you tell the difference? An acid sensitivity test can be performed to determine whether a stone is calcareous or siliceous. While you can do this at home, it’s best done with samples from your stone supplier. Otherwise, you’ll want to perform the test in a very inconspicuous area. Also, if the stone is already in your home and in use, know that the test may not be effective on surfaces that have previously been sealed or polished.

To do the test, you’ll need about 4oz. of a 10-percent solution of vinegar and an eyedropper. Apply a few drops of the acid solution to the stone surface on an area about the size of a quarter. If the stone is calcareous, the acid drops will begin to bubble or fizz. If little or no reaction occurs, the stone can be considered siliceous. Simply rinse the stone with clean water when the test is complete and wipe it dry.

To ensure that you enjoy your natural stone for decades to come, our knowledgeable team of professionals is happy to explain the difference between the various stone types, cover the basics of maintenance with you, and offer tips on cleaning. Whether you visit our 70,000 square-foot headquarters in Westwood, MA or our 30,000 square-foot Milford, CT location, our team will help you choose the best material and maintenance products for your needs. Give us a call at 877 39 STONE or check out our online inventory:


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