Table 2. Apatite compositions, volatile partitioning and concentration of chlorine in the fluid.

Eruption	Minoan*	SD	Cape Riva	SD	Lower Pumice 2	SD	Lower Pumice 1	SD
Sample #			S09–62		S09-23		S09–17
n	22		10(15)		8(9)		8(9)
Composition (wt%)
SiO2	0.23	0.15	0.30	0.25	0.26	0.04	0.23	0.05
CaO	54.18	0.84	54.60	0.36	54.66	0.29	54.71	0.35
P2O5	41.65	0.44	42.64	0.39	42.90	0.32	42.69	0.22
F	2.38	0.30	2.47	0.16	2.45	0.18	2.45	0.09
Cl	1.04	0.10	0.91	0.08	0.76	0.04	0.75	0.03
SO3	0.03	0.03	0.01	0.01	n.d.		0.01	0.01
Total	99.51		100.92		101.03		100.83
Mole fractions of volatile components
XF	0.63		0.66		0.65		0.65
XCl	0.15		0.13		0.11		0.11
XOH	0.22		0.21		0.24		0.24
Partition coefficients
DF ap/melt	29.82		30.41		30.78		28.15
DCl ap/melt	2.96		3.26		2.70		2.64
DS ap/melt	1.21		0.57				0.40
Sructural formula
Ca	9.59		9.49		9.48		9.52
P	5.83		5.86		5.88		5.87
Si	0.04		0.05		0.04		0.04
Cl	0.29		0.25		0.21		0.21
F	1.24		1.27		1.25		1.26
OH	−0.53		−0.52		−0.46		−0.47
Total	16.46		16.40		16.41		16.43
Wt% Cl in fluid†	13.89		12.11		10.15		10.03

n = number of crystal analysed (total number of analyses), SD = standard deviation.

n.d. = not detected.

Mole fractions of volatile components in hydroxyl site computed using the formulae of ref. 77.

X_F, X_Cl, X_OH = mole fraction of fluorapatite, chlorapatite and hydroxylapatite, respectively, in apatite.

D_i^ap/melt = [i] in apatite divided by [i] in glass inclusions (i.e., pre-eruptive melt).

^*Minoan apatite composition from ref. 76.

^†Computed from the relationship X_Cl = 0.011 *(Wt% Cl in fluid[s]), established in ref. 27.