Loop energy: A useful indicator of the hardness of minerals from depth-sensing indentation tests

Toshiaki Masuda, Yasutomo Omori, Ryoko Sakurai, Tomoya Miyake, Mirai Yamanouchi, Yumiko Harigane, Atsushi Okamoto, Katsuyoshi Michibayashi

Research output: Contribution to journalArticle

Abstract

Depth-sensing indentation tests were performed to obtain the loop energy (equivalent to the energy consumed to produce the indentation) and the residual depth of the indentation using a triangular pyramidal diamond indenter for the minerals in Mohs hardness scale except for diamond, as well as other minerals (apophyllite, forsterite, and tourmaline), at a maximum load ranging from 30 to 100 mN. A new graphic presentation is proposed that shows the hardness of minerals in log(penetration depth)−log(loop energy) space. The data for each mineral under different loads give a straight regression line with a slope of 2.6–2.9 (except for talc, which yields a slope of 2.2), while the data for different minerals under a given load yield a straight regression line with a slope of 1.1–1.2. A theoretical analysis of ideal materials, in terms of log(penetration depth)−log(loop energy) space, shows the existence of two series of parallel regression lines with slopes of 3 (data for each mineral at different loads) and 1 (data for different minerals under a given load). The results show a slight deviation between the measured and theoretical slopes, probably reflecting a progressive change in the mechanical properties of the minerals during the indentation tests.

Original languageEnglish
Pages (from-to)96-104
Number of pages9
JournalJournal of Structural Geology
Volume117
DOIs
Publication statusPublished - 2018 Dec

Keywords

  • Depth-sensing indentation test
  • Loop energy
  • Mohs hardness scale
  • New graphic presentation
  • Penetration depth

ASJC Scopus subject areas

  • Geology

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