• journal_title：European Journal of Mineralogy
• Contributor：Zhuming Yang ; Gerald Giester ; Kuishou Ding ; Ekkehart Tillmanns
• Publisher：E. Schweizerbart'sche Verlagsbuchhandlung Science Publishers
• Date：2012-
• Format：text/html
• Language：en
• Identifier：10.1127/0935-1221/2011/0023-2158
• journal_abbrev：Eur J Mineral
• issn：0935-1221
• volume：24
• issue：1
• firstpage：189
• section：Articles

Hezuolinite is a new mineral species occurring as an accessory mineral in the Saima alkaline complex in Liaoning Province, NE China. The mineral occurs in a green-aegirine nepheline syenite as non-metamict grains and is associated with microcline, nepheline, aegirine, biotite, eudialyte, rinkite and titanite. The anhedral crystals are several hundred micrometres in size. The mineral is black with dark-brown streak. It is translucent with a resinous luster. Cleavage or parting was not observed. It is brittle with a conchoidal fracture. The hardness is VHN₁₀₀ 683–964 kg mm⁻² (5.5–6 on Mohs’ scale). The measured density is 4.28 g cm⁻³, and the calculated value is 4.30 g cm⁻³ from the empirical chemical formula. Optically, hezuolinite is biaxial negative, with n > 1.8 and 2V = 75°. The dispersion is strong with r > v. The mineral shows a strong pleochroism, from pale brown to dark brown. The average of twenty-five analyses leads to the empirical formula (Sr_2.15Ce_0.55 La_0.49 Ca_0.49Na_0.12Nd_0.09 Pr_0.03Th_0.03Sm_0.01Eu_0.01)_∑3.98 (Zr_0.82 Fe²⁺_0.14Hf_0.02Mn_0.01)_∑1.00 (Ti_1.38 Fe³⁺_0.36 Fe²⁺_0.14 Al_0.04 Nb_0.02)_∑1.94Ti₂O₈ (Si_2.01O₇)₂, on the basis of O = 22. The simplified formula is (Sr,REE)₄Zr(Ti,Fe³⁺,Fe²⁺)₂Ti₂O₈(Si₂O₇)₂, ideally Sr₂REE₂Zr(Fe²⁺)Ti₃O₈(Si₂O₇)₂.

The five strongest reflections in the X-ray powder-diffraction pattern [d in Å (I)(hkl)] are: 2.98(100)(−204), 3.02(90)(−313), 1.96(90)(024), 2.18(40)(−422), and 2.84(70)(020). The structure was solved and refined in space group C2/m, with a = 13.973(3), b = 5.6984(11), c = 11.988(2) Å, β = 114.10(1) °, V = 871.3(3) Å ³, Z = 2, to R1 = 0.037, wR2 = 0.097.

The structure of hezuolinite is similar to rengeite. The changes of Sr-O, Zr-O and Ti(1)-O distances confirm partial substitutions of REE for Sr, and Fe for Ti. The sites of O(1), O(2) and O(3) of the hezuolinite structure (C2/m) are split into O(1) and O(1′), O(2) and O(2′), O(3) and O(3′) sites in the rengeite structure (P2₁/a), respectively. The Si(1)-O(7)-Si(2) angle in hezuolinite is 175.8°, and is significantly less bent than in rengeite (169.7°). The observed systematic extinctions are in agreement with space group C2/m. Hezuolinite is a member of the perrierite-subgroup and can be considered as a chemical intermediate between rengeite and perrierite.