Portlandite

Portlandite is a mineral that belongs to the calcite group and is classified as a hydroxide. It was first discovered in Portland, England, hence its name. Portlandite has a chemical formula of Ca(OH)2 and is composed of calcium and hydroxide ions.

Characteristics

Portlandite is typically found in the form of colorless to white crystals, which can be transparent or translucent. It has a hardness of 2.5 to 3 on the Mohs scale, indicating its relatively low resistance to scratching. The mineral has a specific gravity of around 2.2, making it relatively light.

Formation

Portlandite is commonly formed as a secondary mineral in the alteration of calcium-rich rocks. It occurs in environments where calcium-rich fluids interact with rocks containing calcium minerals, such as limestone or marble. This interaction leads to the dissolution of calcium minerals and the subsequent precipitation of Portlandite.

Uses

Portlandite has limited practical uses due to its relatively low hardness and lack of durability. However, it is occasionally used as a minor source of calcium hydroxide, which has various industrial applications. Calcium hydroxide, also known as slaked lime, is used in the production of cement, as a pH regulator in water treatment, and in the manufacturing of certain chemicals.

Occurrence

Portlandite is found in various locations around the world. Apart from its type locality in Portland, England, it has been reported in other countries such as Italy, Russia, the United States, and Canada. It is commonly associated with other calcium-rich minerals, such as calcite and aragonite.

See also

• Calcite
• Hydroxide minerals