What is rock salt? Mention its colour and the reason due to which it has this colour.
Hint: As we know that rock salt is a natural mineral composed of sodium chloride in major amounts along with impurities. It generally occurs at evaporite deposits of various minerals such as minerals of the sulfates, halides, carbonates and borates. So here we have to talk about rock salt along with its colour and the reason behind it.
Complete answer: Let us discuss about rock salt as follows:- -Rock salt: It is a type of salt which is a major sodium chloride (NaCl) mineral. It occurs in the form of isometric crystals. It dominantly occurs within the sedimentary rocks as here it has formed from the evaporation of seawater or salty lake water of the nearby coast. -This is the salt which is mostly responsible for the salinity of seawater and also the saltiness of extracellular fluid of many multicellular organisms on earth. When this salt is processed, it becomes edible as well. -The colour of rock salt is generally brown. This brown colour is due to all the impurities present in the salt along with sodium chloride. When the impurities are removed and pure sodium chloride is obtained, it turns into white crystals. -From the above data we can say that rock salt is the solid deposit of sodium chloride which is usually brown in colour due to all the impurities.
Note: -Remember that rock salt can also be found in different colours but in minor quantities due to different composition of impurities. So it can be said that the colour of a salt depends on the composition of impurities as well. Also understand and learn the concepts of the metallurgy chapter so as to answer the questions regarding different ores and minerals.