almost quadrate cushion Basanite shines like a juicy caramel. An unusal gemstone
in a medium size usable to both a ring or a pendant, or even a brooch. (Note!
The colour is darker than in this picture, it can also vary slightly due to
Basaniteis an igneous, volcanic (extrusive)
rock with aphanitisk to porphyritic texture and belongs to the jasper family.
Minerals are usually abundant unit feldspathoid (nepheline or leucite),
plagioclase and augite with olivine and less concentrations of iron-titanium
oxides such as magnetite and ilmenite-ulvospinel; minor alkali feldspar may be
present. Clinopyroxene (augite) and olivine are common as phenocrysts and in the
matrix. The augite contains significantly greater titanium, aluminium and sodium
than that in typical tholeiitic basalt. Quartz is absent, as are orthopyroxene
Basanite occurs both on continents and islands. For example, together with
basalts, they are produced by hotspot* volcanism in Hawaii and the Comoros.
* Hotspots are volcanic regions thought to be fed by underlying mantle that is
anomalously hot compared with the surrounding mantle. They may be on, near to,
or far from tectonic
plate boundaries. Currently, there are two hypotheses that attempt to explain
their origins. One suggests that they are due to hot mantle plumes that rise as
thermal diapirs from the core-mantle boundary. An alternative hypothesis
postulates that it is not high temperature that causes the volcanism, but
lithospheric extension that permits the passive rising of melt from shallow
depths. This hypothesis considers the term "hotspot" to be a misnomer, asserting
that the mantle source beneath them is, in fact, not anomalously hot at all.