**2.4.3. Chlorellestadite**

The mineral chlorellestadite25 [127],[128] was named in 1892 according to American analyti‐ cal chemist R.B. ELLESTAD (**Section 2.4.1**) and the content of chlorine in its chemical composi‐ tion in veinlets cutting contact with metamorphosed limestone. The structure of the mineral ellestadite is shown in **Fig. 49**.

The mineral occurs as a compact mass. The mineral chlorellestadite is associated with diopside, wollastonite, vesuvianite (Ca10Mg2Al4(SiO4)5 (Si2O7)2(OH)4 [129]), monticellite (CaMgSiO4 [130]) and calcite.

<sup>24</sup> The mineral was named after Swedish pharmacologist N.J. BERLIN. The mineral is Al-P analogue of quartz.

<sup>25</sup> The IMA status of the mineral was discredited in 2010.

**Fig. 49** The structure of the mineral chlorellestadite (perspective view along the *c*-axis).

Chlorellestadite is a hexagonal mineral that crystallizes in the space group P63/M with crystallographic parameters *a* = 9.53 and *c* = 6.91 Å, *a*:*c* = 1:0.725, *V* = 543,49 Å3 and *Z* = 2. It has white streaks and a vitreous luster. The color of the mineral is pink, yellowish green, pale rose, orange, but it can also be colorless. The hardness on the Mohs scale is 4½. Calculated and measured densities of the mineral are 3.068 and 3.113 g⋅cm−3, respectively.

#### **2.4.4. Mattheddleite**

Hydroxylellestadite is associated with berlinite24

94 Apatites and their Synthetic Analogues - Synthesis, Structure, Properties and Applications

structure are shown in **Fig. 47** and **Fig. 48**, respectively.

UV light, independently of the excitation frequency [122].

**2.4.3. Chlorellestadite**

[130]) and calcite.

The mineral chlorellestadite25

ellestadite is shown in **Fig. 49**.

25 The IMA status of the mineral was discredited in 2010.

mineral. It is likely to have formed within highly phosphatized, silicate-rich, carbonatemudstone sediments heavily compacted and thermally transformed due to *in situ* bat guano combustion. Known localities, where the mineral hydroxylellestadite can be found, and its

Hydroxylellestadite is a pink or purple-gray hexagonal mineral, which belongs to the space group P63/M. The unit cell parameters are *a* = 9.491, *c* = 6.921 Å, *Z* = 2 and *V* = 539.91 Å3

Calculated density is 3.11 g⋅cm−3. The hardness of the mineral on the Mohs scale is in the range of 3½ to 4½. Hydroxylellestadite shows faded white-yellow fluorescence when irradiated with

**Fig. 48** The structure (perspective view along the *c*-axis) and the crystal habit of mineral hydroxylellestadite.

cal chemist R.B. ELLESTAD (**Section 2.4.1**) and the content of chlorine in its chemical composi‐ tion in veinlets cutting contact with metamorphosed limestone. The structure of the mineral

The mineral occurs as a compact mass. The mineral chlorellestadite is associated with diopside, wollastonite, vesuvianite (Ca10Mg2Al4(SiO4)5 (Si2O7)2(OH)4 [129]), monticellite (CaMgSiO4

24 The mineral was named after Swedish pharmacologist N.J. BERLIN. The mineral is Al-P analogue of quartz.

[127],[128] was named in 1892 according to American analyti‐

(AlPO4 [126]) , another high-temperature

.

Mattheddleite [131],[132],[133],[134] is a mineral with the composition Pb10(SiO4)3(SO4)3Cl2 (LIVINGSTONE et al [131]) or Pb5(Si1.5S1.5)O12(Cl0.57OH0.43) (STELLE et al [134]) which is a lead member of apatite supergroup where phosphorus is totally replaced by sulfur and silicon: Si4+ + S6+ ↔ 2P5+. Mattheddleite was firstrecognized in typical Pb mineralregion at Leadhills, Scotland and named after Scottish mineralogist MATTHEW FORSTER HEDDLE (1828–1897). The *Z* = OH<sup>−</sup> + Cl<sup>−</sup> anion position is zoned from an OH-rich interior to a Cl-rich exterior. Known localities, where the mineral hydroxylellestadite can be found, and its structures are shown in **Fig. 50** and **Fig. 51**, respectively.

Mattheddleite is a colorless or white hexagonal mineral belonging to the space group P63/M. The unit cell parameters are *a* = 9.963 (10.0056 [134]) and *c* = 7.464 (7.4960 [134]) Å, *Z* = ½ (*Z* = 2 [134]) and *V* = 641.63 (649.9 [134]) Å3 . Calculated density is 6.96 (6.822 [134]) g⋅cm−3. The hardness of the mineral on the Mohs scale is 4½.


**Fig. 50** Known localities for the mineral mattheddleite.

**Fig. 51** The structure and the crystal habit of the mineral mattheddleite (perspective view along the *c*-axis).
