What are the two primary methods of identification specified in IS 1123?

Megascopic examination (visual inspection of hand specimens) and microscopic examination (using a petrological microscope on thin rock sections).

What physical properties are evaluated during megascopic examination?

Colour, texture, structure (like bedding planes or foliation), hardness, and primary mineral composition.

How is the hardness of a stone tested in the field according to the standard?

By scratching the stone surface with a pen knife or a standard Mohs hardness testing kit to estimate its relative hardness.

IS 1123

: 1975

Method of identification of natural building stones

CurrentSpecializedTesting MethodMaterials Science · Stones

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IS 1123 outlines the standard procedures for identifying natural building stones using megascopic (hand-specimen) and microscopic examinations. It is primarily used by material scientists and geologists to classify stone types based on mineralogy, texture, structure, and physical properties before they are approved for construction or conservation work.

Method of identification of natural building stones

Quick Reference Values

thickness of thin section0.03 mm (for microscopic examination)

hand lens magnification10x

hardness scale referenceMohs Scale of Hardness (1 to 10)

Practical Notes

Megascopic examination with a 10x hand lens and simple scratch tests is usually sufficient for primary classification on construction sites.

Microscopic examination (thin section petrography) is critical when the stone has a very fine-grained matrix or when evaluating specific mineral degradation that could affect the long-term durability of the stone.

Acid tests (using dilute HCl) should be performed during megascopic identification to easily distinguish calcareous stones (like limestone and marble) from siliceous stones.