Phone: 617.389.1130
Fax: 617.389.3043

We understand that finding the right material can be overwhelming.
Let Colonial Marble’s guide to natural stone help.

Let’s start at the beginning.

Let’s first understand where Natural Stone comes from. The rocks that make up the Earth’s crust fall into 3 groups: Igneous, Sedimentary and Metamorphic.

Metamorphic refers to either Igneous or Sedimentary rock that has been changed by a combination of heat, pressure and chemical reactions beneath the Earth’s crust. For example, when a sedimentary rock such as Limestone is exposed to the intense heat, chemical reactions and pressure under the Earth’s surface, it is transformed into what we call Marble. This is also when Granites, which are categorized as igneous stones, are transformed into schists, sandstones into quartzites and shales into slate.

Technically, all calcareous (made of calcium) rocks, that are capable of taking a polish, can be categorized as marbles.

Marbles are categorized into 4 groups. These groups designate the soundness of the material for building and fabrication purposes. They in no way compare the individual merits of each stone. Each group simply designates certain characteristics that will need to be considered during the processing of the stone. These groups apply only to marble and limestone. Currently, there is no classification scale for Granite, however, Granite is often casually classified in the same way.

Group A Marbles – Sound marbles with uniform and favorable working qualities, containing no obvious geological voids or fissures. These stones do not require any filling or patching and can be used safely for an interior or exterior application.

Group B Marbles – Similar to group A marbles, but may contain some small geological imperfections. These marbles may contain small holes or voids which are filled with epoxy, or polyester resin. These marbles can safely be used in an interior or exterior application.

Group C Marbles – This group of marbles is the largest and most varied. These marbles may contain all or some of the following; holes, voids, lines or separation and structural flaws. It is standard industry practice to repair these variations. Any repairs are usually done at the quarry. Once prepared, these stones are usable for architectural purposes. These marbles are not recommended for exterior use.

Group D Marbles – These are similar to group C but contain a larger proportion of the natural faults listed. Very few stones will be categorized as group D.

Mother Nature intended for natural stone to vary. These variations are what makes natural stone so distinct. We celebrate this distinctness by using stone in everyday applications.

All stones should be sealed prior to use. This allows for time to clean up spills that may later become stains. Some stones are easier to maintain than others. Some stones are harder and more durable than others. Finding the right stone to suit your project isn’t always easy. Colonial Marble’s experts have created an easy to use guide to walk you through.

Knowing the product is crucial to making the right choice.

Quartz

Granite

Marble

Limestone

Travertine

Quartzite

Slate

Terrazzo