measured	value	unit
[SiO₂]	36.4	%
[Al₂O₃]	32.8	%
[Cr₂O₃]	0.18	%
[FeO^T]	10.9	%
[MgO]	3.73	%
[Na₂O]	1.69	%

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