ALLAMOORE
TALC
Talcose rocks usually form from hydrothermal or
regional metamorphism of dolomitic marbles or ultramafic & mafic rocks,
resulting in talc schists, soapstones, and steatites.
The Allamoore Formation (mid-Mesoproterozoic, 1.25
billion years) of western Texas contains commercial quantities of talc
(magnesium hydroxysilicate - Mg3Si4O10(OH)2).
Published research indicates that Allamoore talcose rocks have an unusual
origin. They formed by hydrothermal metamorphic replacement of an
evaporitic lacustrine magnesite succession by hydrothermal connate or meteoric
waters.
Locality:
Bridges Talc Mine (a.k.a. Texola Talc Mine), just north of I-10,
northwest of town of Allamoore, Allamoore Talc District, ~10-12 miles west of
Van Horn, southeastern Hudspeth County, Trans-Pecos Mountains, far-western
Texas, USA (about 31° 05’ 43” North, 105° 01’
33” West).
Allamoore talc (8.3 cm across) from the Precambrian of Allamoore,
Texas, USA.