Mineral Fiber Investigations of the Regional Copper-Nickel Study in Northeastern Minnesota

Our plain-English summary of Mineral Fiber Investigations of the Regional Copper-Nickel Study in Northeastern Minnesota, by R.J. Stevenson (1979).

The study

• Author: R.J. Stevenson
• Published: Annals of the New York Academy of Sciences (1979)
• Type of article: Conference paper
• Our copy: from Johns-Manville's own medical library. The article is still under copyright, so we describe it here rather than post it.

In plain English

This short article described laboratory work by the Regional Copper-Nickel Study in northeastern Minnesota. The work looked at whether mineral fibers could be released when copper-nickel ores from gabbro rocks at the base of the Duluth Complex were processed. The article used the term fiber for any mineral particle more than three times as long as it was wide. The study used nine samples of mineralized gabbro. Amphibole minerals (hornblende, actinolite and cummingtonite-grunerite) ranged from below detectable limits to about 13 volume percent, with an average of 2.3 volume percent. No obvious asbestiform habit was found in the nine process samples. However, an unusual actinolite with asbestiform habit was found in gabbro rocks next to one of the samples. Small-scale ore concentration tests produced tailing slurries, and the water from these was examined for fibers by electron microscopy. The fiber results showed a close straight-line fit (r of 0.998) to a plot of amphibole, but the text breaks off at that point. The article did not study people or health effects.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory mineralogical study of ore samples, with bench-scale ore processing tests and electron microscope fiber counts; no human subjects
• Who was studied: Nine samples of mineralized gabbro (copper-nickel ore) from the base of the Duluth Complex, northeastern Minnesota, taken from 225 kg splits
• Exposure: Amphibole minerals in the ore (hornblende, actinolite, cummingtonite-grunerite) and mineral fibers (particles with aspect ratio greater than 3 to 1) released into tailing slurries during ore processing
• Main results:
  • Amphibole content of the nine samples ranged from below detectable limits to approximately 13 volume percent, with an average of 2.3 volume percent
  • No obvious asbestiform habit was found in the nine process samples
  • An unusual actinolite with asbestiform habit was found in gabbroic rocks adjacent to one of the samples
  • Fiber analysis results showed a linear fit with r of 0.998 to a plot of amphibole; the rest of the sentence is missing from the text

Topics

Medical terms in this study, explained in our Lexicon: Mineral Fiber, Amphibole Group, Hornblende, Actinolite, Cummingtonite-Grunerite, Asbestiform.

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