ROMANORLOVITE, A NEW COPPER AND POTASSIUM HYDROXYCHLORIDE FROM THE TOLBACHIK VOLCANO, KAMCHATKA, RUSSIA
A new mineral romanorlovite was found in upper, moderately hot zones of two fumaroles, Glavnaya Tenoritovaya and Arsenatnaya, located at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. It is associated with avdoninite in both fumaroles, and in Glavnaya Tenoritovaya also with belloite, sylvite, carnallite, mitscherlichite, sanguite, chlorothionite, eriochalcite, chrysothallite, mellizinkalite, <i>etc</i>. Romanorlovite forms prismatic, equant or tabular tetragonal crystals up to 0.1 mm in size, crystal clusters up to 0.5 mm and crusts up to 2X2 mm in area. The mineral is transparent, with vitreous luster. Its color varies from yellow-brown to dark brown, tiny crystals are honey- or golden-yellow. Cleavage was not observed. Romanorlovite is brittle. Its Mohs' hardness is <i>ca</i>. 3. The calculated density varies from 2.72 to 2.79 g·cm <sup>-3</sup>, depending on content of admixed Pb. The mineral is oprically uniaxial (-), ω = 1.727(3), ε = 1.694(2). The Raman spectrum is reported. Chemical composition of the holotype sample (wt %; electron microprobe data, contents of О and H are calculated by stoichiometry): K 21.52, Pb 0.89, Cu 28.79, Zn 0.02, Cl 44.74, O<sub>calc</sub> 4.85, H<sub>calc</sub> 0.41, total 101.22. Its empirical formula calculated based on Cl<sub>25</sub>, with (OH)<sub>4</sub>(H<sub>2</sub>О)<sub>2</sub> is: K<sub>10.90</sub>Pb<sub>0.09</sub>Cu<sub>8.97</sub>Zn<sub>0.01</sub>Cl<sub>25</sub>(OH)<sub>4</sub> · 2H<sub>2</sub>O. The simplified formula is: K<sub>11</sub>Cu<sub>9</sub>Cl<sub>25</sub>(OH)<sub>4</sub> · 2H<sub>2</sub>O(Z = 4). Romanorlovite is tetragonal, I4/mmm. Unit cell parameters are: (1) the holotype: <i>a</i> = 17.5804(7), <i>с</i> = 15.9075(6) Å, V= 4916.5(3) Å<sup>3</sup>; (2) the Pb-enriched sample on which the crystal structure was refined: <i>a</i> = 17.5538(19), <i>с</i> = 15.8620(17) Å, V = 4887.7(9) Å<sup>3</sup>. The strongest reflections of the powder XRD pattern (<i>d</i>,Å-1[<i>hkl</i>]) are: 12.48-56[110], 11.74-36[101], 8.80-100[200], 7.97-34[002], 6.71-40[112], 3.165-32[512], 2.933-80[215, 433], 2.607-38[514]. The mineral is named in honor of the Russian mineralogist and physicist Roman Yu. Orlov (1929-2005) who worked in Dept. of Mineralogy of the Moscow State University.