COLEMAN QUARTZ MINE
The Ouachita Mountains of Arkansas were formed during
the Late Paleozoic Ouachita Orogeny. That mountain forming event was
accompanied by the intrusion of hydrothermal quartz veins in some areas.
The Coleman Quartz Mine allows for close examination and collection of
spectacular quartz crystals from these veins.
Ouachita Mountains - the Ouachita Orogenic Belt of Arkansas consists
principally of folded & faulted Paleozoic sedimentary rocks. The mountains
do not have high topographic relief because of their age. The Ouachitas
formed during the Late Pennsylvanian and Permian. Two hundred and fifty
million years worth of weathering and erosion has reduced them considerably.
Coleman Quartz Mine - the main pit. Rocks are excavated from the
pit by heavy machinery and dumped on an adjacent platform for collecting.
Location:
Coleman Quartz Mine, south of Jessieville, northern Garland County,
west-central Arkansas, USA. 34º 39.700' N, 93º 06.072' W.
Coleman Quartz Mine - wall of the main pit showing abundant hydrothermal
quartz veins (whitish) intruding quartz arenites of the Middle Ordovician
Blakely Sandstone. The quartz veins are Late Pennsylvanian to Permian in
age.
Coleman Quartz Mine - large masses of hydrothermal vein quartz (SiO2).
Hydrothermal vein quartz (white - SiO2) of Late
Pennsylanian-Permian age intruding quartz arenite (brown) of the Blakely
Sandstone (Middle Ordovician).
Hydrothermal quartz vein having abundant, well-formed crystal faces and
crystal terminations.
Hydrothermal vein quartz (white) intruding quartz arenites (light brown) of
the Blakely Sandstone (Middle Ordovician).
Hydrothermal quartz vein having abundant, large crystals.
Hydrothermal quartz vein (white; Late Pennsylvanian-Permian) intruding quartz
arenite (brown; Blakely Sandstone, Middle Ordovician). Sample is 4.1 cm
tall.
Hydrothermal quartz vein (whitish; Late Pennsylvanian-Permian) intruding
quartz arenite (brown; Blakely Sandstone, Middle Ordovician). Field of
view: 4.3 cm across.
Quartz arenite from the Middle Ordovician Blakely Sandstone.
Very thin hydrothermal quartz veins (whitish-gray wisps) of Late
Pennsylvanian-Permian age are present throughout the rock. Field of view:
2.55 cm across.
Quartz
(SiO2) (4.2 cm tall) from hydrothermal vein intruding Blakely
Sandstone. Well-formed hexagonal quartz crystals are common at Coleman
Mine. The crystals are clear/colorless (“rock crystal”) or whitish
(“milky quartz”).