Nepheline, also called nephelite, occurs in intrusive and volcanic rocks with low silica, and in their associated pegmatites. It is used in glass and ceramic manufacturing and other industries, and has been investigated as an ore of aluminum.
Nepheline is the characteristic mineral of alkaline plutonic rocks, particularly nepheline syenites and nepheline gneisses. It occurs in beautiful crystal form with mica, garnet, and sanidine feldspar on Monte Somma, Vesuvius, Italy. For detailed physical properties, see feldspathoid (table).
Nepheline appears only in quartz-free alkaline rocks in association with other alkali-rich or silica-poor minerals (other feldspathoid, Na-Amphiboles, Na- pyroxenes). It forms as primary magmatic minerals through the crystallization of Na-rich Si-poor magmas; it may result from the assimilation of limestone by basic or intermediate magmas.
| No | Compound | Result % |
|---|---|---|
| 01 | SiO2 | 61.29 |
| 02 | Al2O3 | 20.59 |
| 03 | Fe2O3 | 0.28 |
| 04 | TiO2 | 0.01 |
| 05 | CaO | 1.98 |
| 06 | MgO | 0.32 |
| 07 | K2O | 5.69 |
| 08 | Na2O | 7.21 |
| 09 | LOSS (1025℃) | 2.28 |
