Silver

Seán Manchester (from his writings) on silver's properties:

A silver crystal.

Pure silver has the highest thermal conductivity (the non-metal diamond and superfluid helium II are higher) and one of the highest optical reflectivities, albeit a poor reflector of ultra-violet. Silver has a brilliant white metallic lustre and is slightly harder than gold. It is very ductile and malleable, exceeded in these properties only by gold and palladium. Sterling silver (92.5% silver, with copper or other metals) is used for silverware and jewellery.

Silver occurs native and in ores incuding argentite (Ag2S) and horn silver (AgCl). Lead, lead-zinc, copper, copper-nickel, and gold ores are other prinicipal sources of silver. Commercial fine silver is at least 99.9% pure. Commercial purities of 99.999+% are available. Silver is stable in pure air and water, but tarnishes when it is exposed to air or water containing ozone or hydrogen sulphide; the latter forming a black layer of silver sulphide which can be cleaned off with diluted hydrochloric acid.

For the exorcist or any person wanting to ward off evil entities, silver is invaluable. I am never without a crucifix made of the finest silver available, and I prefer to always use silver when dispensing the Sacraments.

Vampires have a strong aversion to mirrors and silver (sometimes used in the making of mirrors). The invention of the silvered-glass mirror is credited to German chemist Justus von Liebig in 1835. His process involved the deposition of a thin layer of metallic silver onto glass through the chemical reduction of silver nitrate. This silvering process was adapted for mass manufacturing and led to the greater availability of affordable mirrors. Nowadays, mirrors are often produced by the vacuum deposition of aluminium (or sometimes silver) directly onto the glass substrate. The mirrors in my home are all made of silvered-glass.

In the past, silver crosses and icons were frequently displayed in houses for protection against evil spirits, particularly vampires. Various other methods have been used to ward off or even rid a contaminated area of vampires. Driving a stake of ash or aspen wood through the undead's heart during the daylight hours will end its nocturnal wanderings beyond the tomb. Until 1823, when it was made illegal, it was common practice in England to drive a wooden stake through the heart of suspected vampires. According to folklore, thorns of wild roses and garlic will also keep vampires away. Pure or fine silver is hateful to such supernatural predatory wraiths as vampires, and this element can also be used to protect from all manner of other demonic manifestation.