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Watch Back: Cotterite - The World’s Rarest form of Quartz

An example from the Museum's collection of the mineral cotterite, a variety of quartz with a metallic pearly lustre.

Join National Museum of Ireland - Natural History's Geology Curator, Dr Patrick Roycroft, for an online talk to discover the world’s rarest form of mineral quartz.

Cotterite is the rarest variety on Earth of the most common mineral on Earth. Cotterite is a type of quartz that was only ever found in County Cork and that shows a unique trait. Instead of looking glassy, which is the lustre of all well-behaved quartz (e.g. amethyst, citrine, rock crystal, prase), cotterite displays a bizarre and distinctive silvery metallic sheen. Yet there is no metal! For quartz, as far as we currently know, this trait has only ever appeared once on Earth, in just one mineral vein, and found just once back in 1875 by a lady known for 137 years only as ‘Miss Cotter’ from Rockforest, after whom the mineral variety was named. This talk will explain this most weird-looking of quartzes and reveal not only who ‘Miss Cotter’ was but also who are her closest living relatives. 

This pre-recorded talk was broadcast on YouTube on Friday, 18 August 2023, as part of Heritage Week 2023 programming. For the most up-to-date information about NMI - Natural History, inlcuding opening hours please visit 'Visitor Info'.

For more highlights about the collections at the Museum visit our online talk series 'Tales from the Decant' 

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Natural History

Natural History,
Merrion Street,
Dublin 2,
D02 F627

+353 1 677 7444