keith.] TALC DEPOSITS OF NORTH CAROLINA. 437 
exceed an acre, it is customary to find several of the metamorphic 
varieties associated in each area. The dunite type prevails in the 
southwestern portion of the mountains in North Carolina and the 
soapstone type in the northeastern. In the French Broad Valley, 
about in the middle of the belt, soapstone is by far the most common, 
over 80 separate areas being known below Asheville. In this district 
alone are there any considerable bodies of workable talc. They are 
concentrated in a belt 4 or 5 miles wide on each side of the French 
Broad River between Marshall and Alexander, and will be shown in 
the forthcoming Asheville geologic folio. In the forthcoming Mount 
Mitchell folio, and in the Cranberry folio, now in press, many other 
areas of soapstone are represented. 
The talc or hydrous silicate of magnesia was formed by alteration 
of a basic rock which contained originally an abundance of magnesian 
silicates. In most cases, however, there were formed in addition to 
the talc a number of other silicates containing magnesia, such as 
tremolite, actinolite, hornblende, and chlorite. These are practically 
the same minerals which occur as impurities in the talc of the Chero- 
kee marble formation. As a rule, the talc is equaled or exceeded in 
amount by the other silicates, and the rock formed by them is a soap- 
stone. This is especially the case in Watauga and Ashe counties, 
where the other silicates so predominate that the rock is often of no 
value even for the uses of soapstone. 
Why the talc predominates in one region and the other silicates in 
another is a matter of doubt. In many places a portion of the mass 
is mainly talc or a very pure soapstone, while other portions may be 
filled with the silicate minerals. Where there are differences of this 
kind in a single soapstone body the purer soapstone and talc are usu- 
ally at the borders of the mass, being influenced in some manner by the 
contact of the adjoining rocks. Besides the talc of this form, pure 
talc is also found in veins a few inches in width passing here and 
there through the mass of the rock. This form of the mineral is usu- 
ally fibrous or foliated and free from the objectionable silicates. Talc 
veins of this character seem to be of later formation than the large 
bodies of talc and the soapstones. These veins are also found in the 
serpentine and dunite masses, together with veins of chlorite and 
asbestos. 
The talc so far mined has been taken from the veins and from the 
purer portions at the borders of the soapstone mass. Although the 
amount of talc disseminated through the soapstone is infinitely greater, 
it is not practicable to -separate it from the chlorite and other minerals 
which are intermingled with it. In following the vein talc there is a 
fair amount of certainty as to the product, both in quality and in quan- 
tity. In the bordering bodies of talc the quantity is much greater 
and can be figured upon fairly well. The quality is quite uncertain, 
