THE MINERAL MELANOPHLOGITE

• Chemistry: C2H17O5Si46O92 , Silicon Oxide with organic compounds.
• Class: Organic Minerals
• Uses: Only as mineral specimens.
• Specimens

Melanophlogite, besides having a great name, is a very rare mineral being found in only a few sites. Some mineral purists might not agree that it is a mineral, as they tend to dislike any organic connection to minerals (see anapaite). In this example, not only is there a connection, but organic chemicals are obviously in the formula! Melanophlogite does form crystals, and attractive ones too; however, the actual symmetry is still in doubt. Individual crystals of melanophlogite appear cubic, but they could just be pseudo-cubic (see boleite). An examination of the formula for melanophlogite (C2H17O5Si46O92) reveals a large amount of SiO2 or silica. It might be tempting to conclude that it is just organically impure quartz, but melanophlogite isn't. If it were quartz, it would have quartz's structure and symmetry, and it definitely does not have these. As long as one can ignore the organic chemical connection, melanophlogite is its own mineral because it is naturally formed, a crystalline solid (repetitive), formed with no direct biological connection, and composed of a set chemical formula. The mineral whewellite, having a formula of CaC2O4 - H2O and being the salt of oxalic acid, has a similar problem.

PHYSICAL CHARACTERISTICS:

• Color is colorless or white.
• Luster is vitreous.
• Transparency crystals are transparent to translucent.
• Crystal System is tetragonal or possibly isometric.
• Crystal Habits include botryoidal, globular clusters and cubes (if it is isometric, they are cubes; if tetragonal, they are pseudo-cubic crystals).
• Cleavage is not present.
• Fracture is conchoidal.
• Hardness is 6.5 - 7.
• Specific Gravity is 2.0+ (well below average)
• Streak is white.
• Associated Minerals include calcite, sulfur and other sedimentary minerals.
• Notable Occurrences are limited to Giona Mine, Girgenti and other sites in Sicily, Italy.
• Best Field Indicators are crystal habit, hardness, very low density and locality.