6 types of stone used as landscape decorative rock and the differences between them

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Kalamazoo Materials, Inc.

Our quarries mine specific types of quality granite, rhyolite, and quartzite deposits that produce exceptional colors resulting in our picturesque product line. This allows designers to truly turn their landscapes into a work of art. We choose to exclusively mine deposits that not only produce vivid color but also meet the quality, consistency, and long term needs of our clients, their clients and ultimately the environment. Even though this has not been an easy task to accomplish, as it is already difficult to mine on any land, we go the extra mile to beautify and preserve our landscapes. Our products outperform in all applications because we continue to test the material in rigorous industry specifications such as hardness, chemical compound, mineral compound, before and after the final product.

Why does this make a difference? In comparison with sandstone, shale, or limestone, granite does not melt from weathering or from drip irrigation systems. Granite will also retain its color and will not decompose from wear or weather as quickly as other materials. When you are spending time and money to set your complex or project apart from the rest, why use a product that will not hold up under normal use? This will cost you more in upkeeps because of increased “top dressing” to maintain a consistent look and may lose its color altogether.

It is important when you are trying to make your project aesthetically pleasing and stand out from others, that you choose a product that will perform in the long term and will be available for several years after the project is complete. That is why we not only search for quality granites but also for quarries that will produce them for many years. Every quarry we operate has a long time reserve of product to ensure that material will be around for any touch up or new construction you encounter down the road. This is not something that every other producer can claim or support.

We have been in business for the last 35 plus years and have earned a reputation for customer service and quality products. We will stand behind our products as well as offer you, the client, support that may be needed. This is something that most producers do not or can not offer you.

Below are more detailed explanations of the differences in landscape rock products.

1. Granite
   This is an intrusive rock, meaning it has intruded the crust of the earth from the mantle but never made it out to the atmosphere. This rock tends to cool slowly because it is “insulated” by the surrounding mass. Due to slow cooling, the individual minerals have time to organize and “grow”, creating a crystalline, coarser grained texture. Granites can be fine, medium or coarse grained based on the general rule of thumb that “the faster a rock cools and consolidates, the finer the grain size”. This is a very hard, durable rock.
   
   
2. Rhyolite
   This is an extrusive rock, meaning it has been extruded outside the surface of the earth as a lava flow. This rock cools quickly and therefore has a fine grained composition where the individual mineral constituents generally are not discernible with the unaided eye. This is a very durable rock.
   Chemically and mineralogically, rhyolite is granite, the former just being the extrusive equivalent of the intrusive material.
   
   
3. Quartzite
   Quartzite is sandstone made up primarily of quartz grains (very little feldspar or mic). The grains of this rock are fused together by heat and pressure (metamorphism) resulting in very strong quartz cementing. Where most sandstones with weak to moderate cementing tend to fracture through the cement and around the grains, quartzite tends to break indiscriminately across the grains and the cement. In effect, the rock breaks more like glass. This rock is very durable.
   
   
4. Shale
   This is a product that is exclusively a product of sedimentation in a very low energy environment such as calm lakes, estuaries, and inland seas. Shale can be thinly bedded or massively bedded depending on the frequency of clay loading of the depositional waters. Shales preserve organic and fossil materials well because of the fine grain size and common rapid deposition environments that quickly bury the organism. Shale is usually a softer, friable rock that crumbles easily. This is not a durable stone.
   
   
5. Sandstone
   A material created by the process of sedimentation of poorly to well sorted grain sizes originating from the breakdown and transport of contributing “host” rock. Grain size in a sandstone ranges from the very fine to pebble/ cobble conglomerate. Grain size is a direct indicator of distance from the source of the grains. General rule of thumb here is “the larger the grain size, the closer to the source”. The energy of water or wind that moves the particles also plays an important role, i.e., a huge storm event can move boulders tens of miles from their source and deposit them haphazardly with fine grained sediment, creating a chaotic, well-graded sandstone deposit. Another rule of thumb – “the more consistent the grain size, the more consistent the energy in the depositional
   system”. The cement within a sandstone that holds all the individual grains together is frequently CaCO3, and we know what happens when this is exposed to oxygen and water … it begins to break down from the inside out – not very durable.
   
   
6. Limestone
   In its pure form limestone is chemically precipitated from ocean and inland sea waters that are super-saturated with the by-products of single celled microorganisms that are primarily calcium carbonate. Limestones also form by the dying of much larger, active reef-building organisms such as corals and algae that have secreted calcareous skeletal matter. Limestone (CaCO3) “melts” in the presence of water and oxygen. By-products of this breakdown are CO2 and CaO – this is why caves are found almost exclusively in limestone deposits.