Amethyst with Hollandite ホーランダイト入りアメジスト 78.71 ct Star Burst Cushion Cut 30.10 x 20.20 x 15.80 mm the most exciting find Made in 2020 near Brejinho, Bahia, Brazil max888

Amethyst with Hollandite Inclusions.

A Amethyst with these inclusions have been found in 2020 near Brejinho, Bahia, Brazil.

At first the visual test appeared to be hollandite. This material belongs to a group of similar members ,but is different from the well known “star hollandite” from Madagascar.

First of all the star hollandite is an intergrowth of needles crossing each other, in this case instead the needles departing from a single point.

All the research and test has been performed at the Università La Sapienza in Rome:

1- A scanning electron microscope ( SEM ) Carl Zeiss SEM EVO 50 + energy dispersive spectrometer EDS.

2-Microprobe EMP + wavelength dispersive spectroscopy (WDS).

With these two analysis we reached a conclusion:

Analogy with other hollandite types:

This new one

Empirical formula:

a (Ba0,981 Pb0,256 Na0,097 K0,013)Σ1,348m ( Mn4+4,916 Mn3+2,504 Ti0,339 Si0,160 Fe3+0,046 Al0,035)Σ8,000O16

ideal formula:Ba(Mn4+6Mn3+2)O16

Ferrihollandite                                                                                                                                 empirical formula:

(Ba0,793 Sr0,222 Na0,024 K0,009)Σ= 1,048 (Mn4+ 5,624 Ti0,318 Fe3+1,016 Mn3+ 0.910 Al0,129 Zn 0,003)Σ=8.000 O16

ideal formula:Ba(Mn4+6Mn3+2)O16

Ferricoronadite

empirical formula:

( Ba0,32 Pb1,03)Σ= 1,350 (Mn4+ 4,85 Ti0,49 Fe3+ 1,35 Mn3+ 1.18 Al0,09 Zn0,04) Σ=8.000 O16

ideal formula: Ba(Mn4+6Mn3+2)O16