OPAL WITH PECULIAR POROSITY FROM SZKLARY (THE SUDETES)

摘要

In an old, closedown nickel mine at Szklary, a previously unknown modification of opal has been found. The change of its colour and transparency dependent on the moisture content is the peculiar feature of this opal, which reveals specific microporosity under the electron microscope. Pores are 1-50 μm in diameter and resemble small bubbles of water vapour escaping from boiling jelly. This type of porosity is an essential argument for the hydrothermal origin of the opal investigated and can provide insight into the unsolved problem of the origin of silification within the Szklary serpentinite massif.