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© Kaegen Lau

Blakeburn Amber (Allenby Fm., 52.5-48 Ma)

Barrelcactusaddict

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“Blakeburn Amber”
Coalmont, British Columbia
Allenby Fm. (Princeton Group)
52.5-48 Ma
 
Weight: 0.8g
Dimensions: 16x16x13mm
 
Lighting:
140lm LED
 
The final entry in a series of ten, detailing various rare ambers from European, Asian, and North American localities.
 
This is a fine example of an in-situ piece of amber. The matrix is high-volatile type B bituminous coal, which contains small portions of methane; it has a bright vitreous luster due to it containing over 90% vitrinite (a “maceral”, or component of coal, derived from woody plant tissue).
 
Geology of the Allenby Fm.:
Within the Tulameen Basin lies the Tulameen Coalfield, which covers approximately 6.2 square miles (10 sq. km.), and is located about 12.5 miles (20 km.) northwest of Princeton, B.C.; within the Allenby Fm. is three members/layers: an upper member of sandstone and conglomerate 600 m thick, a lower sandstone member 100-150 m thick, and a middle member 130 m thick; the middle member is predominantly mudstone and shale and contains two coal seams, the upper seam containing amber. The main seam lies 25-40 m above the lower seam, is 15-21 m thick, and is of much higher quality than the lower seam: it is from this layer that much of the mining was done.
 
Botanical Source:
Nearby, the Allenby Fm. is composed of three Members, the middle being the Vermillion Bluffs Shale: it is known for its rich deposits of plant fossils. Approximately 9.3 miles (15 km.) southeast of the Tulameen Coalfield, is the famous Thomas Ranch locality: here, the majority of the plant fossils consist of cupressaceous remains, “Metasequoia occidentalis” being the most common; at Tiger Mountain (Washington State, USA), Eocene-aged amber occurs alongside Metasequoia and Taxodium leaf imprints, which are plentiful. It is quite possible that Blakeburn and Tiger Mountain ambers were derived from a Cupressaceae source tree.
 
History of Mine:
In 1899, analyses on the coal of the Tulameen Basin were submitted to the Geological Survey of Canada, and mining began in 1904 in the Blakeburn Creek area; the owners of the mines, Coalmont Collieries, Ltd., created 5 mines over the next 30 years, with mines No. 1 and No. 2 opening in 1913. No. 3 and No. 4 began production in the 1920s, but were shut down in the 1930s due to fires and flooding. It was in the No. 4 mine that a tragic incident occurred on August 13, 1930: an explosion killed 45 men, and was believed to have been caused by a buildup of methane (released from the high-volatile type B coal, mentioned earlier) from closed-off mining areas. The official explanation by the mining company claimed methane was not a major contributing factor; interesting, considering that the fire bosses of the mine asserted to the workers beforehand that the mines were gas-free. From 1900 to 1940, 2.2 million tons of coal were produced, with the No. 5 Mine closing in 1940. Sporadic exploration has been done in the area since 1960, and in 2002, Compliance Coal Mining was planning to open a mine in the Tulameen Basin.
 
Sources:
“The Eocene Thomas Ranch flora, Allenby Formation, Princeton, British Columbia, Canada”; Article in “Botany”; Dillhoff, et. al. 2013
 
“Overview of the Coalbed Methane Potential of Tertiary Coal Basins in the Interior of British Columbia”; BCGS Geological Fieldwork 2002; Barry Ryan
 
“Coal Petrology of the Tulameen Coalfield, South Central British Columbia”; Western Washington University; V. Eileen Williams 1978
 
“Stratigraphy of Eocene Rocks in a Part of King County, Washington”; U.S. Geological Survey; James D. Vine 1962

Copyright

© Kaegen Lau

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  • Taken with SAMSUNG SAMSUNG WB35F/WB36F/WB37F
  • Focal Length 4.3 mm
  • Exposure Time 1/33
  • f Aperture f/3.1
  • ISO Speed 200
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