Melanophlogite Locality: Fortullino, Rosignano Marittimo , Livorno Province , Tuscany , Italy ( Locality at mindat.org ) Size: 6.1 x 4.9 x 4.3 cm. This is a large matrix rich with 1-3mm spherical aggregates of the CH4-group-containing species Melanophlogite. Melanophlogite is a chemically strange mineral species. A classic example for this locality. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Melanophlogite
A rare porous silica polymorph — a zeolite-like clathrate that traps organic molecules and CO₂ inside its cages.
Intro adapted from Wikipedia (CC BY-SA).
Melanophlogite is an IMA-recognized mineral species in the organic mineral class, with the chemical formula C₂H₁₇O₅·Si₄₆O₉₂.
It crystallizes in the cubic crystal system (space group Pm3n).
Key properties: Mohs hardness 6.5–7; specific gravity 1.99–2.11; Adamantine luster; optically isotropic.
IMA symbol Mp, IMA status: approved, named in 1876.
A late-stage, low-temperature mineral in sulfur deposits (Racalmuto, Sicily, Italy); in low-temperature hydrothermal veins in association with metamorphosed sedimentary manganese deposits (Chvaletice, Czech Republic).
It is found associated with Sulfur, calcite, \opal, " cristobalite, quartz, dolomite, celestite, pyrite, marcasite, rhodochrosite, magnesite.
Its name comes from the Greek for black and to be burned, in allusion to the fact that some specimens of the mineral turn black when heated.