Good Stone Properties

1.Specific Gravity: A good building stone should have a specific gravity of 2.7 or more. Heavy stones are suitable for construction of abutments, dams, docks, harbors, etc. while lighter types are used in building construction.
2.Hardness: For use in highly loaded structures, such as in the construction of bridges, piers and abutments and marine structures, and especially where they are subject to friction, stone hardness is an essential requirement.

3.Water Absorption: Moisture reduces the strength of rocks and such rocks with high moisture content or absorption have low strength values. All stones are more or less porous, but the percentage of stone by weight after 24 hours should not exceed 0.60 for good absorption.
4.Weathering: A good building stone should have better weathering properties. It should be able to withstand the adverse effects of various environmental and external agencies like rain, frost, wind, etc.
5.Ease of Dressing: Stone should be relatively soft, yet durable, compact grained and uniform for ease of dressing. It should be free of veins and cleavage planes. Such a stone is called freestone. Stones should be such that they can be easily carved, shaped, cut and dressed. This is an important consideration from an economic point of view.

6.Appearance: The appearance of a stone in relation to the design is of great importance from an architectural point of view. Appearance depends upon the colour and ease with which the stone can be dressed, rubbed or polished. Deep colours, however, in sedimentary rocks are due to oxides of iron in the cementing material, which, upon exposure to the atmospheric influences, either fade away or disfigure and strain the surface on account of the rusting of iron. The stones which are to be used for face work should be attractive in appearance and should be of uniform colour and free from clay holes, spots of other colour, bands, etc. Stones with lighter shades are preferable, because even if they fade a little they will not show a striking difference and spoil the appearance.