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24-008
Alteration and Geochemistry of Clinkers in the San Juan Basin,
New Mexico
Devlon R. Shaver
New Mexico Institute of Mining and Technology.
Socorro, New Mexico.
Virginia T. McLemore
New Mexico Bureau of Geology and Mineral
Resources. Socorro, New Mexico
ABSTRACT
Clinkers are the result of a seam of coal catching fire and
burning the surrounding rocks. The fires caused the sur-
rounding rocks to be baked at high temperatures, removing
organic material and partially forming glass. These rocks
become hard, orange, and brick like, forming clinker. The
purpose of the study is to determine their potential to con-
tain economic levels of critical minerals, including Rare
Earth Elements. Some clinkers contain over 200 ppm total
REE.
INTRODUCTION
The San Juan Basin consists of 24 individual coal fields
present in New Mexico. Coal mining has been conducted
in the state since the late 1800s, with the San Juan basin
becoming heavily developed during the early and mid-20th
century. Extensive mining operations took place for over a
century in the Basin with numerous recent large operations
taking place and countless small pits being operated. The
majority of the coal resources found in the San Juan Basin
are late Cretaceous in age, and are part of the Menefee and
Crevasse Canyon formations of the Mesa Verde Group,
and the Fruitland Formation. [1] The coal resources of the
San Juan Basin are extensive, and typically occur in lensed
shapes of varying thicknesses [2]. Coal seams that have,
through erosion and time, become exposed to the elements
can gradually break down into humates over time. Clinkers
are found in areas where underground coal fires have taken
place, altering the coal seam and the surrounding rock lay-
ers. Clinker deposits can be found in the Gallup, Bisti, and
Standing Rock coal fields within the San Juan Basin, all
areas extensively mined for coal deposits. (Figure 1). These
deposits represent sedimentary beds that surrounded coal
seams that burned underground for long periods of time,
exposing the surrounding layers to extreme heat.
Figure 1. Map showing clinker deposits (stars) and
coal fields (colored polygons) in the San Juan Basin of
northwestern New Mexico
24-008
Alteration and Geochemistry of Clinkers in the San Juan Basin,
New Mexico
Devlon R. Shaver
New Mexico Institute of Mining and Technology.
Socorro, New Mexico.
Virginia T. McLemore
New Mexico Bureau of Geology and Mineral
Resources. Socorro, New Mexico
ABSTRACT
Clinkers are the result of a seam of coal catching fire and
burning the surrounding rocks. The fires caused the sur-
rounding rocks to be baked at high temperatures, removing
organic material and partially forming glass. These rocks
become hard, orange, and brick like, forming clinker. The
purpose of the study is to determine their potential to con-
tain economic levels of critical minerals, including Rare
Earth Elements. Some clinkers contain over 200 ppm total
REE.
INTRODUCTION
The San Juan Basin consists of 24 individual coal fields
present in New Mexico. Coal mining has been conducted
in the state since the late 1800s, with the San Juan basin
becoming heavily developed during the early and mid-20th
century. Extensive mining operations took place for over a
century in the Basin with numerous recent large operations
taking place and countless small pits being operated. The
majority of the coal resources found in the San Juan Basin
are late Cretaceous in age, and are part of the Menefee and
Crevasse Canyon formations of the Mesa Verde Group,
and the Fruitland Formation. [1] The coal resources of the
San Juan Basin are extensive, and typically occur in lensed
shapes of varying thicknesses [2]. Coal seams that have,
through erosion and time, become exposed to the elements
can gradually break down into humates over time. Clinkers
are found in areas where underground coal fires have taken
place, altering the coal seam and the surrounding rock lay-
ers. Clinker deposits can be found in the Gallup, Bisti, and
Standing Rock coal fields within the San Juan Basin, all
areas extensively mined for coal deposits. (Figure 1). These
deposits represent sedimentary beds that surrounded coal
seams that burned underground for long periods of time,
exposing the surrounding layers to extreme heat.
Figure 1. Map showing clinker deposits (stars) and
coal fields (colored polygons) in the San Juan Basin of
northwestern New Mexico