A Short Discussion on the Difference of Flagstone (bluestone) and Kearney Stone Flagstone (bluestone colonial) is sandstone of relatively uniform grain size having characteristically uniform splitting properties parallel to the planar stratification. The hardness, color and resistance to weathering is controlled by the mineral composition. Most of the bluestone is bluish-to-bluish gray or reddish-to-reddish-gray in color. Much of the bluestone was formed in rapidly moving water producing the thin laminations to allow the rock to split. Grain size tends to be a fine to medium sand. This rock commonly includes cross-bedding. Since the sediment was deposited in a stream setting with one direction of flow, cross-bedding is parallel to the direction of stratification. This factor may allow the rock to be affected by weathering quicker. Also, this sandstone is often interbedded with shales (clay) as the stream environment often changed with water conditions. This would also result in small clay content within the sandstone, which in turn would reduce the amount of silica both of the grains and cement. The reddish color is due to hematite and higher clay content in the bluestone. The blues and grays are due to clay grains mixed in with the sediment (silica). Kearney Stone appears to be a quartzitic sandstone. This rock contains a high percentage of quartz grains and is cemented by quartz. The Kearney Stone is coarser-grained. Depending upon the percentage of impurities, the Kearney Stone will hold up well to weathering with this texture. Occasional grains of impurities (mostly clay or iron). The bluestones contain a higher amount of impurities compared to the Kearney Stone. With less amount of impurities, the Kearney Stone would be more resistant to weathering. Kearney Stone would be slightly tougher to cut or split because it is more homogeneous rock containing the silica. Because the Kearney Stone is believed to have originated as a beach deposit, the sand grains are well sorted, again making this stone slightly tougher to weather. Any color on the weathering surface is due to the mineral composition such as iron. A change of appearance due to weathering of the Kearney Stone may be a minimum due to the high silica content. As a beach deposit, the Kearney Stone would have a greater volume of minable stone on a property.
Posted on: Thu, 27 Jun 2013 01:27:43 +0000
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