1908 ] 
Monazite and Monazite Mining 
71 
Monazite- Bearing Rock 
Monazite has been observed in the Carolinas in several types of 
rock, among which are gneiss, pegmatized gneiss and schist, peg- 
matite, and different varieties of granite. The occurrence of mon- 
azite in ordinary pegmatite masses is in large masses of crystals. 
These have been found varying from an ounce or two to several 
pounds in weight in the mica mines of Mitchell and Madison 
counties, N. C. 
Most of the pegmatized gneiss bodies which are rich in monazite 
represent phases of the Carolina gneiss in which the original 
nature of the rock has been largely obliterated as a result of the 
addition of new minerals and the recrystallization of the original 
ones into pegmatitic material. The texture developed during this 
pegmatization is in many cases porphyritic, in which the feldspar 
phenocrysts assume somewhat of an augen form. The feldspar 
phenocrysts range in size from some smaller than a grain of wheat 
to others the size of a walnut. The porphyritic gneiss may grade 
into less or more highly pegmatized gneiss, and from the latter into 
regular pegmatite- This gradation may be between two separate 
beds or from one part to another of the same bed. In those beds 
or portions of beds where there has been little pegmatization mon- 
azite occurs sparingly. The same is true where pegmatization has 
been complete and but little of the original gneiss remains. It is, 
then, the beds of gneissic rock which are rich in secondary quartz 
and contain numerous small masses of feldspar throughout that 
carry the most monazite. In such rocks there is generally much 
biotite, with graphite and perhaps some muscovite and other acces- 
sory minerals, as well as abundant quartz and feldspar. The 
quartz occurs in layers or scattered grains throughout the rock, 
inclosing and replacing the other constituents. The feldspar crys- 
tals chiefly replace, though they partly displace the other minerals 
of the rock, Monazite in a rock matrix almost invariably pos- 
sesses crystal form, often with brilliant faces. 
A typical example of rich monazite-bearing rock could be 
described as follows: The chief constituents of the rock are 
quartz, feldspar (mostly the potash variety), biotite, graphite, 
muscovite, monazite, and a little zircon. It has a banded stuc- 
