X-Ray Diffraction and Vibrational Spectroscopic Characteristics of Hydroxylclinohumite from Ruby-Bearing Marbles (Luc Yen District, Vietnam)

Table 1

Average composition and chemical formula of hydroxylclinohumite from Vietnam.

Oxide	wt.%	Ion	Average a.p.f.u.
SiO2	38.5(1)	Si^4+	3.997
TiO2	0.52(3)	Ti^4+	0.041
MgO	57.6(2)	Mg^2+	8.911
FeO	0.48(2)	Fe^2+	0.042
F	2.89(8)	F^−	0.948
O=F	−1.22(3)
H2O*	1.52(3)	OH^−*	1.052
Total	100.3(3)

a.p.f.u.: atoms per formula unit; numbers in parentheses are standard deviations (1𝜎) referred to last decimal digit.
∗OH=2-F, H₂O content back-calculated from the calculated OH content, other elements (Na, K, Ca, Al, Mn, Cr, Ni, Ca, and Cl) below detection limits.