Opal Replacing Bivalve Fossil US minerals antimony sulfosalt Franckeite consisting of

antimony sulfosalt Franckeite consisting of somewhat "sword"-shaped crystals oriented into spherical aggregates

Here we have one of the great old classics from Mexico

This mine is probably best known for its amazing pink Rhodochrosite and green Fluorite associations

There's a very large amount of space between the top layer and the underlying Quartz crystals on the matrix

hollow cavity on the base of the piece where a good amount of preexisting Anhydrite once grew

Opal Replacing Bivalve Fossil US minerals antimony sulfosalt Franckeite consisting ofOne of the great classics in terms of Australian Opal. The myriads of Opal found in Australia ranges from the finest Black Opals in the world to many precious multi color Opals including what I believe are the most iconic Opal fossil pseudomorphs extant. This piece was mined in the mid 1960s and features a well preserved bivalve mollusk shell which has been not only fossilized but partially replaced by gemmy multi color Precious Opal. The top portion