Hardystonite

Hardystonite is a rare calcium zinc silicate mineral that was first discovered in 1899 in Franklin, New Jersey, USA. It is named after the township of Hardyston in Sussex County, where the type locality (Franklin Mine) is situated. Hardystonite is known for its fluorescent properties, which are best observed under shortwave ultraviolet light.

Description

Hardystonite is a member of the wollastonite group of minerals. It is typically colorless or white in its pure form, but impurities can give it a range of colors, including pink, brown, and gray. The mineral has a vitreous luster and a white streak. It is transparent to translucent and has a hardness of 3.5 on the Mohs scale. Hardystonite is usually found in massive form, but it can also occur as granular or fibrous aggregates.

Occurrence and Formation

Hardystonite is a rare mineral that is found in only a few locations worldwide. It is typically associated with zinc ore deposits and is often found in association with other rare minerals such as clinohedrite, willemite, and franklinite. The type locality for hardystonite is the Franklin Mine in New Jersey, USA, which is known for its unique assemblage of rare minerals.

Hardystonite forms in metamorphic rocks, specifically in skarns, which are calcium-rich rocks that have been altered by contact with hot, mineral-rich fluids. The formation of hardystonite is closely related to the geological processes that form zinc ore deposits.

Uses

Due to its rarity, hardystonite has no significant industrial uses. However, it is a sought-after mineral among collectors, particularly those who specialize in fluorescent minerals. When viewed under shortwave ultraviolet light, hardystonite fluoresces a bright blue color, which is a result of the presence of trace amounts of divalent europium ions.

See Also

• List of minerals
• Fluorescent minerals
• Franklin, New Jersey