The concave bottom of caldera, about 5 km in diameter, consists of carbonatite, agglomerate, tuff, feldspathic rocks ( fenites ) and basic dykes.
32.
Less common types of chondrules may be dominantly composed of feldspathic material ( again either glassy or crystalline ), silica, or metallic Fe-Ni and sulfides.
33.
Some varieties include " feldspathic greywacke ", which is rich in feldspar, and " lithic greywacke ", which is rich in tiny rock fragments.
34.
Six sandstone names are possible using the descriptors for grain composition ( quartz-, feldspathic-, and lithic-) and the amount of matrix ( wacke or arenite ).
35.
It is predominantly composed of mature, poorly cemented quartz sandstone, though several distinct facies have been identified on the basis of grain size, feldspathic content, and sedimentary structures.
36.
The Goudini formation is more feldspathic and finer grained than the Skurweberg Formation, which is characterised by fairly thick bedded medium to coarse grained, light grey, slightly feldspathic quartzose sandstone.
37.
The Goudini formation is more feldspathic and finer grained than the Skurweberg Formation, which is characterised by fairly thick bedded medium to coarse grained, light grey, slightly feldspathic quartzose sandstone.
38.
Formed during the Jurassic Period, the Yarragadee Formation is composed primarily of non-marine fluviatile feldspathic, poorly sorted sandstones which are porous and poorly cemented, hence allowing for considerable groundwater reserves.
39.
The results showed the minerals came from an acidic, high saline hydrothermal solution at temperatures of 140�C . The interaction of hydrothermal fluids with feldspathic rocks precipitated the ore minerals ( Nickel 2002 ).
40.
Olivine-rich chondrules may contain parallel plates of that mineral, surrounded by a continuous shell of olivine and containing feldspathic glass between the plates; these are known as " barred " textures.
