Home > Pseudomorphs – March 3 > MS1511 Quartz after Melanophlogite

Quartz after Melanophlogite

Melanophlogite is a curious mineral with a long history dating to the early nineteenth century; von Lausalx (1876) named the species by combining Greek roots melas for black and phlego for burning. Melanophlogite turns black when heated. It is now known that melanophlogite is a silicate clathrate, in other words it is cage-like structure of silica that encloses (and traps) guest molecules (Kolosev & Geiger, 2003). In the presence of high temperature water, i.e. conditions of hydrothermal alteration, melanophlogite recrystallizes as quartz (Skinner & Appleman, 1963). In other parts of the world, numerous occurrences of quartz pseudomorphs after melanophlogite have recently come to light, e.g. Dr. Housley's article on mindat.

Agate is a banded variety of fine-grained quartz, admired for its beauty and complexity. One variety known since the mid-20th century is Blue Lace Agate from Namibia. Some vein sections of Blue Lace Agate show surfaces covered in cubic crystals. For years, such pseudomorphs were regarded as replacements after fluorite. Modern research indicates that melanophlogite is a more likely precursor. This sample of gem rough, polished on one surface, reveal its internal structure and has surface covered in cubic crystals to 6 mm on edge. This specimen shows minor chipping on the cube forms, likely from rough travel from the African desert. Apparently no longer in production. A good example.

Price: $200

Item code: MS1511

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