Answer
Some silicate structures have double chains in which half of the tetrahedrons of one chain are bonded to tetrahedrons in another chain through oxygen atoms. The minerals with double silicate chains are called amphiboles.
Work Step by Step
Some silicate structures have double chains in which half of the tetrahedrons of one chain are bonded to tetrahedrons in another chain through oxygen atoms. The minerals with double silicate chains are called amphiboles, and the repeating unit in the crystal is $Si_{4}O_{11}^{ 6-}$. Half of the tetrahedrons are bonded by two of the four corner O atoms, and half of the tetrahedrons are bonded by three of the four corners, joining the two chains together. The bonding within the double chains is very strong, but the bonding between the double chains is not so strong. This structure often results in fibrous minerals such as asbestos.
