Question

Colemanite is:
A.$N{a_2}{B_4}{O_7}.10{H_2}O$
B.$C{a_2}{B_6}{O_{11}}.5{H_2}O$
C.$NaB{O_2}$
D.${H_3}B{O_3}$

Answer 1

We must remember that colemanite is a borate mineral which is found in hydrous deposits of alkaline waters. It is not a primary product; it is a secondary mineral that is formed by the alteration of borax and ulexite. It is also called a hydrated calcium borate due to the presence of water of crystallization in the molecular formula.

Complete step by step answer:
We must have to remember that the Colemanite is an important ores of boron. Due to its distinct properties, it is widely used in industrial areas.
It was first found in $1884$ in furnace creek in death-valley. It was named after William Tell Coleman, the owner of Harmony Borax Works, where the Colemanite was found.
Physically it is colorless, whitish, yellowish or greyish in colour. It has a granular to a coarsely crystalline structure.
The chemical composition is given by the chemical formula - $C{a_2}{B_6}{O_{11}}.5{H_2}O$ .
We can observe that this compound has calcium and boron present in it.
It has distinct characteristics of fluorescence. And at very low temperatures, it shows pyroelectric and piezoelectric properties.
Hence, the correct answer to the question is option B.

Note:
We must have to know that the colemanite is found in masses in Paleogene and Neogene sediments. Commercially, Colemanite is a very important source of borate and boric acid. There are many borate minerals found in nature. The various minerals are namely, boracite, borax, kernite, ludwigite, ulexite, inyoite, priceite, sussexite, tincalconite, etc. As we know that the borate mineral structures exhibit a boron oxide in either triangular or tetrahedral geometry. Where oxygen and hydroxyl groups are present at the corners or vertices.