IS 1123:1975 is the Indian Standard (BIS) for method of identification of natural building stones. 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
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Primary Identification Method | Macroscopic examination (colour, texture, fracture) and simple field tests (hardness with knife, acid test). | Mandatory petrographic examination using microscopy as per EN 12407. | EN 12440:2016 |
| Granite Definition | A crystalline, igneous rock of coarse to fine-grained texture, consisting chiefly of feldspar and quartz. | A granular igneous rock where quartz constitutes 10-50% of felsic components and the feldspar ratio is defined. | ASTM C119 - 22 |
| Limestone Identification | Identified by its fine-grained, non-crystalline texture and vigorous effervescence with dilute acid. Can be scratched by a penknife. | Identified as a sedimentary rock composed principally of calcite (CaCO3), which is confirmed by petrographic analysis. | EN 12670:2019 |
| Hardness Assessment | Qualitative test using a penknife (e.g., 'scratched by penknife' or 'not easily scratched'). | Not used for formal identification; quantitative methods like Mohs scale or standardized abrasion resistance tests (e.g., EN 14157) are used for performance characterization. | General Practice / EN Test Methods |
| Commercial Marble Definition | Defined geologically as a recrystallized limestone capable of taking a good polish. | Broader commercial term for a crystalline rock of calcite, dolomite, or serpentine that can take a polish (includes non-metamorphic rocks). | ASTM C119 - 22 |
| Inclusion of 'Laterite' | Included as a distinct category, identified by its porous nature, cellular structure, and reddish-brown color. | Not listed as a main category for dimension stone. Would be classified under a broader petrographic family (e.g., iron-rich sedimentary rock). | ASTM C119 / EN 12440 |