Lignite, also known as leonardite, mined lignin, brown coal, and slack, is an important constituent to the oil well, drilling industry. Lignite, or leonardite as it will be referred as hereafter, is technically known as a low rank coal between peat and sub-bituminous. Leonardite was named for Dr. A.G. Leonard, North Dakota's first state geologist, who was a pioneer in the study of lignite deposits. Leonardite is applied to products having a high content of humic acid. Humic acid has been found to be very useful as a drilling mud thinner.

Leonardite came into wide usage when introduced as a replacement for quebracho in 1947. Quebracho was imported from South America and widely used as a

Mining lignite, Black Hills Bentonite
Leonardite is mined from shallow beds with front-end loaders.
drilling mud thinner until restrictions during World War II caused this import to suffer. Since this time leonardite has gained acceptance as having some qualities as a fertilizer due to its high humic acid content as well as a drilling mud thinner.

Black Hills Bentonite entered the leonardite business in 1987 with the acquisition of reserves and the building of a processing plant. The plant is near the town of Glenrock, Wyoming, with the reserves approximately ten miles north of that location.

Black Hills Lignite, LLC, sells custom packaged leonardite products to all the major drilling fluids companies. these products are sized, packaged, and sold in various different ways. Leonardite can be processed into a granular form down to a powder. Leonardite is packaged into 50 lb. sacks, up to 2000 lb. sacks. Leonardite can be shipped by rail, bulk or bag as well by truck. We look forward to providing continued service to the leonardite markets of today and that of the future.