Table 1 Activation energy E_a for single-crystal amphiboles, covering a broad range of Fe/(Fe + Mg) ratios, as reported in the literature.

Impedance spectroscopy

arfvedsonite

~ 1

0.4 (σ_||)

Schmidbauer et al.²⁴

edenitic-hornblende

0.75

0.58 (σ_||)

Schmidbauer et al.²⁵

edenite

0.36

0.70–0.80

Hu et al.²²

kaersutite

0.25

0.61 (σ_||)

Schmidbauer et al.²⁵

Mg-hornblende

0.22

0.73–1.06 (σ_||)

Schmidbauer et al.²⁵

tremolite

0.01

3.79

Shen et al.³¹

dc electrical resistance

riebeckite (crocidolite)

~ 1*

0.69 (σ_||)

Littler and Williams⁴³

riebeckite

~ 1*

0.9 (σ_||)

Parkhomenko⁴⁵

riebeckite

0.95

0.77 (σ_||)

Della Ventura et al.²⁶

riebeckite

0.95

0.53 (σ_||) (300–720 K)

This work

not given

0.19

0.54(σ_||) and 0.57(σ_⊥)

Tolland²⁷