This aesthetically pleasing miniature combination of well-formed metallic steel-grey crystals of Acanthite after Argentite with small scalenohedral Calcite crystals is also an extreme rarity. Despite being a well-known silver producer, Peregrina mine is not known for specimens of silver-bearing minerals. The rich crystals presented here were previously labelled as Argentite - presumably because of their shape and chemistry - but it is now known that Argentite is only stable above 177 degrees C, below which it converts to Acanthite. These crystals measure up to 0.7 cm across and are attractively associated with gemmy colourless to opaque white scalenohedral Calcite crystals measuring to 1.1 cm, many of which are double terminated. A real Mexican rarity for the silver species connoisseur. Note that close-up photos where taken under daylight conditions.
