Use and Care Manual

2
Types of Natural Stone
Classifications of Stone Types
Because not all stones are the same, it is important to understand the differences in order to recognize the unique
characteristics of each type of natural stone. The composition of each stone affects its density, absorption rate,
hardness and appearance, which ultimately will determine how the stone should be cared for and how to keep
its natural beauty intact with proper maintenance.
Natural stone can be classified into two general categories according to its composition: siliceous stone or
calcareous stone. Knowing the difference is critical when selecting cleaning products.
Siliceous stone is composed mainly of silica or quartz-like particles. It tends to be very durable and relatively
easy to clean with mild acidic cleaning solutions. Types of siliceous stone include granite, slate, sandstone,
quartzite, brownstone and bluestone.
Calcareous stone is composed mainly of calcium carbonate. It is sensitive to acidic cleaning products and
frequently requires different cleaning procedures than siliceous stone. What may work on siliceous stone may not
be suitable on calcareous surfaces. Types of calcareous stone include marble, travertine, limestone and onyx.
Density and Hardness
Measuring the hardness of a stone can help determine its strength. Knowing the hardness of a stone is especially
helpful when choosing and considering a stone for a particular application. Density is measured by the Mohs
scale of mineral hardness. If a stone can be scratched by a known mineral on the scale, then it is softer than that
mineral.
The following chart gives an example of a similar material to the ones on the Mohs scale:
Hardness
Level
Scale Mineral Equivalent Surfaces
1 Talc Talcum Powder
2 Gypsum Plaster of Paris
3 Calcite Marble, Travertine, Limestone, Slate
4 Fluorite Platinum
5 Apatite Knife Blade, Iron
6 Orthoclase/Feldspar Granite, Glass
7 Quartz Hardened Steel, Granite
8 Topaz Emerald, Topaz
9 Corundum Ruby, Sapphire, Abrasives
10 Diamond Diamond, Abrasives
Due to its hardness and scratch
resistance, granite is ideal for
use on countertops and floors
and can be used in high-traffic
applications. Softer stones, such as
marble, travertine and limestone,
are generally used in lighter-duty
applications because they can
scratch easier.