Basalt is an extrusive igneous rock that usually contains 45–52%of silica (SiO2) and in comparison, to most common igneous rocks, is rich is iron-, calcium-, and magnesium-oxides. Basalt occurs indifferent colours like dark, grey, and greyish dark. Since basalt formation involves rapid cooling, it is characterized by fine to very fine grains. It formed by the rapid cooling of volcanic magma on the surface of Earth. Basalts are abundantly available in different parts of the world, including India. Basalt contains very good mechanical and physical properties and the main advantage is good resistance to chemically active environments. Basalts are composed mainly of fine grains of plagioclase feldspars and pyroxenes. It exhibits a fine-grained texture. Based on the mineralogical analysis, some of the minerals occur predominantly in granite, especially quartz, feldspar and mica, and typically it occurs as an intrusive igneous rock. Basalt contains feldspar, pyroxenes and olivine, and typical properties like black colour with vesicles from which gas escaped during their formation. Basalt occurs as an extrusive volcanic igneous rock. In both rocks, the physical properties are quite different from each other. Basalt has a density of 1934.5 kg/m3 at a temperature of 1050 ℃ and 2091.8 kg/m3 at 1100℃. Water absorption varies significantly from 15.8% at 1050 ℃ and 8.90% at 1100 ℃ temperature. Similarly, there is a significant variation in porosity with temperature as exemplified by 31.5% porosity at 1050 ℃ and 19.9% at1100 ℃. Based on mineralogical analysis basalt rocks are suitable for building materials. Selection of building stones is based on different criteria like mineralogical composition, textures, mineral grain size, durability, and hardness of the rock. The rock is formed by extrusive / Volcanic Igneous rock.

Mineralogical point of view it is made up of Feldspar, Pyroxene, Amphibole, and Olivine. It is presence of Black and grey with vesicles formed by escaping gases.

Selection of building material is very important in construction industries considering texture, grain sizes, and hardness. Durability, hardness, mineralogical composition, and appearance play avital role in the selection of building materials. These parameters are quite common all over the world. Fine-grained rocks will give more strength and are very hard whereas coarse-grained rocks are comparatively less strong. The rock should not be altered or change of colour even after exposure to air. Chemical composition especially lime, silica, and alumina are highly influencing in rock properties. Silica content in granite is quite high than basalt. It is 46.5 to 51.5% in basalt. Alumina is in basalt; it is 15 to 19%. Potassium oxide is 3 to 6% in basalt. The soda component in is 7.5 to 11.5% in basalts. Results of this work on basalt as building materials shows that there are significant variations in their basic physical parameters, which are very important for building materials. The difference in water absorbability at varied temperatures in basalt is very interesting. Chemical properties in basalt show significant variations in their silica and iron-oxide composition.

In short, the physical properties and the chemical composition are significantly different in case of basalt.

Based on mineralogical composition, texture, hardness, and grain sizes these rocks are suitable to use as building materials. Most of the civil engineering projects depend on raw materials like basalt as these rocks are hard, mostly compact, and are widely available at affordable price. Basalt aggregate powder is the raw building raw materials that are most demanded in the construction industry. Absorbability of basalt at varied temperatures show very good signature for building materials.

Reference:

C. Agasnalli, H.C. Hema, T. Lakkundi et al. 2022. Integrated assessment of granite and basalt rocks as building materials. Materials Today: Proceedings 62. Pp. 5388–5391

Amygdaloidal Basalt: Amygdaloidal texture refers to the presence of gas bubbles or vesicles that were trapped in the lava during its eruption and later filled with minerals after the rock solidified. These fillings, called amygdules, are typically rounded or almond-shaped (hence the name, derived from the Latin word for “almond”).