Crystal System: Trigonal
Status of Occurrence: Confirmed Occurrence
Chemical Composition: Tin oxychloride
Chemical Formula: Sn21Cl16O(OH)14O6
Method(s) of Verification: not known.
- Supergene: minerals on an artificial substrate
Scanning electron micrograph of platy abhurite crystals discovered, within alteration 'blisters' on tin ingots salvaged from the wreck of S.S. Liverpool off the coast of Anglesey. © National Museum of Wales.
Introduction: abhurite occurs exclusively on tin ingots in shipwrecks. It is formed by the chemical reaction between the tin and the chloride ions present in seawater. First described from a shipwreck in the Red Sea, abhurite was approved as a mineral species in 1983. However, since that time the criteria for defining a substance as 'a mineral' have been changed (Nickel, 1995). There are substantial anthropogenic factors involved in the formation of abhurite (i.e. creation of metallic tin by mining and smelting, loading the tin onto a ship and taking that ship to the area in which it sinks and the process of abhurite formation can begin). According to the latest criteria that define whether something is or is not a mineral, it is most unlikely that this would be validated as a mineral species by the International Mineralogical Association (IMA) were it to be discovered today.
Occurrence in Wales: only one 'occurrence' of this substance is recorded from Wales, that being from a shipwreck off the Anglesey coast. Tin ingots recovered from the SS Liverpool, which sank off the coast of Anglesey in 1863 following a collision, are coated with abhurite in 'blisters'.
- SS Liverpool wrecksite: coarse bladed abhurite crystals line 'blisters' on the surface of tin ingots recovered from the wreck of the SS Liverpool, which sank off the coast of Anglesey in 1863 following a collision.
- Nickel, E.H., 1995. Definition of a mineral. Mineralogical Magazine, 59, 767-768.