SECTION 13 

 GEOLOGIC POLLUTION PROBLEMS OF LAKE SUPERIOR 

 Albert B. Dickas, Ph.D. 



ASBESTIFORM MINERALS 



Background 



On 17 February, 1972, the U.S. Environmental Protection Agency first 

 stated that the presence of the trace mineral cummingtonite in the Wis- 

 consin portion of Lake Superior constituted interstate pollution. This 

 statement was made part of preliminary evidence being gathered in the now 

 famous "Reserve Mining Case" (Reserve Mining Company versus United States 

 of America, No. 74-1291). In December of that same year the first public 

 statement was made of concern over the relationship of the presence of as- 

 bestos and potential public health hazards of residents of the Lake 

 Superior Basin (Great Lakes Research Advisory Board, International Joint 

 Commission, 1975). Since then a number of detailed investigations of the 

 distribution and health effects of asbestos have been undertaken. 



Prior to this time, the region was internationally known as an econo- 

 mic source of silver (historically), copper, as well as high grade (hema- 

 tite) and low grade (taconite) iron ore, but not asbestos in any commer- 

 cial quantity. Thus little research has been done on the distribution of 

 this mineral within the Great Lakes area. Although the effects of inhaled 

 asbestos are reasonably well known to be the causative agent of the 

 disease asbestosis (a scaring of the lungs by increased fibrous tissue 

 growth), the effects of ingested asbestos have only recently been con- 

 sidered by the scientific and medical community. 



Mineralogy, Chemistry and Morphology 



The term asbestos is defined by Dana (1954) as constituting the fib- 

 rous varieties of serpentine and amphibole, the fibers of which are some- 

 times very long, fine, flexible, easily separable by the finger and look 

 like flax. The term is derived from the Greek for "incombustible". 

 Generically, the term is used to describe fibrous hydrated silicates, con- 

 sisting of 40-60 percent silica in combination with oxides of iron, magne- 

 sium and other metals. The minerals differ in their chemical and physical 

 properties, such as fiber diameter, flexibility, tensile strength and sur- 

 face properties. 



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