melanite การใช้

• The dark matrix consists of biotite, aegirine-augite and melanite.
• Biotite occurs in some of these rocks, and melanite also is present.
• Melanite is found in some of the lavas, as in the leucite syenites.
• Their pyroxene is principally aegirine or aegirine-augite; some of them are rich in melanite.
• Its chemical formula is O 7 It occurs mostly in skarns with melanite adjacent to an alkali syenite and has no economic value.
• The accessory minerals are apatite, cancrinite, calcite, titanite and iivaarite, a dark-brown titaniferous variety of melanite-garnet.
• Their lusters range from vitreous to subadamantine, to almost metallic in the usually opaque melanite, which has been used to simulate black diamond.
• Among the accessory minerals biotite, brown hornblende, hauyne, iron oxides and apatite are the commonest; melanite and nepheline may also occur.
• The abundance of melanite is very unusual in igneous rocks, though some syenites, leucitophyres, and aegirine-felsites resemble borolanite in this respect.
• Other minerals common in minor amounts include sodium-rich pyroxene, biotite, titanite, iron oxides, apatite, fluorite, melanite garnet, and zircon.
• These have a radiate arrangement externally, but are of irregular structure at their centres; it is interesting to note that in both rocks melanite is an important accessory.
• There are two kinds of composition, one is high alkali, alumina, silicon and barium containing melanite garnet; the other is high in potassium with nepheline and hauyne.
• In Finland, melanite bearing nepheline rocks have been found and described as ijolite, but the only other locality for melanite-leucite-syenite is Magnet Cove igneous complex in Arkansas.
• In Finland, melanite bearing nepheline rocks have been found and described as ijolite, but the only other locality for melanite-leucite-syenite is Magnet Cove igneous complex in Arkansas.
• The brightly glittering black sands of the beaches are made of crystals of melanite garnet, barkevikite hornblende, and magnetite eroded from the uncompahgrite lava fragments in the agglomerates that overlie the fossil beds.
• The latter is the rarest and most costly of the garnets, with three of its varieties topazolite ( yellow ), melanite ( black ), and demantoid ( green )  sometimes seen in jewelry.
• At the margins of the outcrop patches of nepheline syenite occur; usually the nepheline is decomposed, but occasionally it is well preserved; the other ingredients of the rock are brown garnet ( melanite ) and aegirine.
• The presence of the following minerals precludes a rock from being classified as a lamproite : primary plagioclase, melilite, monticellite, kalsilite, nepheline, Na-rich alkali feldspar, sodalite, nosean, hauyne, melanite, schorlomite or kimzeyite.
• Sanidine, melanite, hauyne and perovskite are frequent accessory minerals in these rocks, and many of them contain melilite in some quantity, The well-known leucitite of the Capo di Bove, near, Rome, is rich in this mineral, which forms irregular plates, yellow in the hand specimen, enclosing many small rounded crystals of leucite.