measured	value	unit
[SiO₂]	37.0	%
[TiO₂]	0.84	%
[Al₂O₃]	31.3	%
[Cr₂O₃]	0.16	%
[FeO^T]	8.77	%
[NiO]	0.1	%
[MgO]	5.14	%
[Na₂O]	2.46	%

tables:

Table 1-1. Chemical compositions of tourmaline.Elemental abundances are normalized to a total of 100 cg/g of Ota, Tsutomu (2019) Tourmaline in a Mesoarchean pelagic hydrothermal system: Implications for the habitat of early life, Precambrian Research, 334. more