Melilitite

Melilitites are ultramafic volcanic rocks consisting essentially of melilite and pyroxene. Perovskite is also commonly present. If a mode can be determined, the appropriate name can be obtained from Fig.1:. If the mode cannot be determined and a chemical analysis is available, then the TAS classification should be used.

Fig.1: Modal classification of volcanic rocks containing melilite based on the values of melilite (Mel), olivine (Ol) and clinopyroxene (Cpx). After Streckeisen, 1978.

Melilitite dyke of Prete della Scimmia (1km North of Lago Piccolo, Monticchio lake) shows phenocrysts of a Akermanitic melilite, Ti-rich salitic clinopyroxene and opaque oxide in a holocrystalline groundmass also containing nepheline, leucite and hauyne together with apatite, perovskite and Ti-rich garnet. Ocellar textures composed of calcite, magnetite, clinopyroxene and nepheline are also observed.

Bibliography

• De Fino, M., La Volpe, L., Peccerillo, A., Piccarreta, G., & Poli, G. (1986). Petrogenesis of Monte Vulture volcano (Italy): inferences from mineral chemistry, major and trace element data. Contributions to Mineralogy and Petrology, 92(2), 135-145.
• D'Orazio, Massimo, et al.(2007). "Carbonatites in a subduction system: the Pleistocene alvikites from Mt. Vulture (southern Italy)." Lithos 98.1: 313-334.
• Jones, A. P., Kostoula, T., Stoppa, F., & Woolley, A. R. (2000). Petrography and mineral chemistry of mantle xenoliths in a carbonate-rich melilititic tuff from Mt. Vulture volcano, southern Italy. Mineralogical Magazine, 64(4), 593-613.
• Beccaluva, L., Coltorti, M., Di Girolamo, P., Melluso, L., Milani, L., Morra, V., & Siena, F. (2002). Petrogenesis and evolution of Mt. Vulture alkaline volcanism (Southern Italy). Mineralogy and Petrology, 74(2-4), 277-297.
• Peccerillo, A. (2005). Plio-quaternary volcanism in Italy (Vol. 365). Springer-Verlag Berlin Heidelberg.

Photo
Green pyroxene, melilite and leucite. Prete della Scimmia melilitite. PPL image, 2x (Field of view = 7mm)	Green pyroxene, melilite and leucite. Prete della Scimmia melilitite. PPL image, 2x (Field of view = 7mm)	Green pyroxene, melilite and leucite. Prete della Scimmia melilitite. PPL image, 2x (Field of view = 7mm)
Pyroxene, melilite (rectangular crystals) and leucite (isotropic). Prete della Scimmia melilitite. XPL image, 2x (Field of view = 7mm)	Pyroxene, melilite (rectangular crystals) and leucite (isotropic). Prete della Scimmia melilitite. XPL image, 2x (Field of view = 7mm)	Pyroxene, melilite (rectangular crystals) and leucite (isotropic). Prete della Scimmia melilitite. XPL image, 2x (Field of view = 7mm)
Pyroxene, melilite (rectangular crystals) and leucite. Prete della Scimmia melilitite. PPL image, 10x (Field of view = 2mm)	Blue hauyne crystal. Prete della Scimmia melilitite. PPL image, 10x (Field of view = 2mm)	Leucite crystal. Prete della Scimmia melilitite. PPL image, 10x (Field of view = 2mm)
Leucite crystal. Prete della Scimmia melilitite. PPL image, 10x (Field of view = 2mm)	Blue hauyne crystal. Prete della Scimmia melilitite. PPL image, 10x (Field of view = 2mm)	Calcite-filling a vescicle. PPL image, 10x (Field of view = 2mm)
Calcite-filling a vescicle. Prete della Scimmia melilitite. XPL image, 10x (Field of view = 2mm)	Melilite crystal. Prete della Scimmia melilitite. PPL image, 10x (Field of view = 2mm)	Melilite and hauyne crystals. Prete della Scimmia melilitite. PPL image, 10x (Field of view = 2mm)
Melilite crystal. Prete della Scimmia melilitite. PPL image, 10x (Field of view = 2mm)	Melilite crystal. Prete della Scimmia melilitite. PPL image, 10x (Field of view = 2mm)	Melilite crystal. Prete della Scimmia melilitite. XPL image, 10x (Field of view = 2mm)
Melilite crystals and calcite-fillng vescicle. Prete della Scimmia melilitite. XPL image, 10x (Field of view = 2mm)	Melilite crystal. Prete della Scimmia melilitite. XPL image, 10x (Field of view = 2mm)	Melilite crystal and green pyroxene. Prete della Scimmia melilitite. PPL image, 10x (Field of view = 2mm)
Melilite crystal. Prete della Scimmia melilitite. XPL image, 10x (Field of view = 2mm)	Melilite crystal. Prete della Scimmia melilitite. XPL image, 10x (Field of view = 2mm)