This Winter in Dublin, discover the pearly lustre of the world's rarest quartz with one of our online curator talks from NMI - Natural History.

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.

Update 2024!

Since the airing of this online talk there has been a once in a life-time find! Ben O’Driscoll, aged seven, from Mallow in Co Cork, was the first person in 150 years to find a piece of cotterite — the world’s rarest form of quartz in the world! Ben found the cotterite specimen on the same lands as the original discovery and where his family now live. National Museum of Ireland Geology Curator, Dr Patrick Roycroft, confirmed the find and was one of many excited geologists to present Ben with a certificate at a special event in University College Cork. 

This video was first recorded and published as part of Heritage Week 2023. 

If you have any questions that you would like answered, please email us at educationnh@museum.ie