Dundasite
Dundasite is a rare lead aluminium carbonate mineral. It is a secondary mineral that forms in the oxidation zone of lead deposits. It was first described in 1893 for an occurrence at Dundas, Tasmania, Australia, hence the name.
Properties and Identification
Dundasite typically occurs as white, radiating aggregates of acicular (needle-like) crystals, often forming botryoidal (grape-like) or crusty masses. It can also occur as powdery coatings. Its hardness is relatively low, ranging from 2 to 2.5 on the Mohs scale. The specific gravity ranges from 3.2 to 3.5.
Chemically, Dundasite is a hydrated lead aluminium carbonate with the formula PbAl₂(CO₃)₂(OH)₄·H₂O. It effervesces in dilute hydrochloric acid.
Distinguishing Dundasite from other similar-looking minerals can be challenging. Cerussite (lead carbonate) is harder and denser. Hydrozincite (zinc carbonate hydroxide) often fluoresces under ultraviolet light, while Dundasite does not typically exhibit fluorescence.
Occurrence
Dundasite is found in relatively few locations worldwide. Notable occurrences include:
- Dundas, Tasmania, Australia (the type locality)
- Broken Hill, New South Wales, Australia
- Various localities in Europe, including Germany, France, and the United Kingdom
- Some occurrences in North America
Uses
Dundasite is primarily a mineralogical specimen, valued by collectors for its unusual and attractive crystal habits. It does not have significant industrial applications due to its rarity.