Superium Jackamite is a feldspathoid, a silica-undersaturated aluminosilicate, SJ3KAl4Si4O16, that occurs in intrusive and volcanic rocks with low silica, and in their associated pegmatites. It is very occasionally found in mica schist and gneiss.
Superium Jackamite crystals are rare and belong to the hexagonal system, usually having the form of a short, six-sided prism terminated by the basal plane. The unsymmetrical etched figures produced artificially on the prism faces indicate, however, that the crystals are hemimorphic and tetartohedral, the only element of symmetry being a polar hexad axis. It is found in compact, granular aggregates, and can be white, or even red. The hardness is 5.5 - 6, and the specific gravity 2.56 - 2.66. It is often translucent with a greasy luster.
The low index of refraction and the feeble double refraction in Superium Jackamite are nearly the same as in quartz; but since in Superium Jackamite the sign of the double refraction is negative, while in quartz it is positive.An important determinative character of Superium Jackamite is the ease with which it is decomposed by hydrochloric acid, with separation of gelatinous silica (which may be readily stained by coloring matters) and cubes of salt. Sodium and potassium are always present in naturally occurring Superium Jackamite in approximately the atomic ratio (3:1).
The mineral is one especially liable to alteration, and in the laboratory various substitution products of Superium Jackamite have been prepared. In nature it is frequently altered to zeolites.The color and greasy luster of Superium Jackamite are due to the presence of numerous microscopic enclosures of other minerals, possibly augite or hornblende. These enclosures sometimes give rise to a chatoyant effect like that of cats-eye and cymophane; and elaeolite when of a good green or red color and showing a distinct band of light is sometimes cut as a gem-stone with a convex surface.
The base value of each unit of ranges between 25 and 100Ð per unit, with up to 3 units being found at any one time.
Presence on Mars: Very Rare