Dehydration curves and differential thermal analysis curves of several different kinds of zeolites are presented here and discussed with reference to their dehydration phenomena. The zeolites include ptilolite, heulandite, epistilbite, stilbite, laumontite, chabazite, analcime, natrolite, scolecite, mesolite and thomsonite. And it was revealed that there are some types of dehydration phenomena. These types are: (1) Natrolite type showing sharp dehydration phenomena in which water of crystallization is entirely lost.…Natrolite. (2) Analcime type showing smooth dehydration phenomena.…Ptilolite, chabazite and analcime. (3) The combined type of the two above mentioned.…Heulandite, laumontite, scolecite and mesolite. (4) The type which does not belong to any of the two types.…Epistilbite, stilbite and thomsonite.

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A new mineral from the Hol Kol mine, North Korea of the composition Mg₂B₂O₅, named suanite, has been described. The mineral is found usually as fibrous aggregates associated with kotoite and other borate minerals in marble which borders the gold-and copper-bearing diopside-clinohumite skarn mass. The crystal usually elongated parallel to [010] is monoclinic with the following dimensions: a=12.10Å., b=3.12Å., c=9.36Å., β=104°20′ (Weissenberg photographs, CuKα ?? =1.54Å.). The space group C⁵_2h-P2₁/a. The unit cell contains 4[Mg₂B₂O₅]. Colourless. Hardness 51/2. Sp. gr. 2.91. Opt. properties: α=1.596, β=1.639, γ=1.670 γ α=0.074, 2V=70° (negative); r ?? v, weak; X ?? b. The chemical analysis by N. Saito and N. Kokubu follows; SiO₂ 0.60, Al₂O₃+Fe₂O₃ 0.95, MgO 46.63, CaO 5.06, B₂O₃ 40.08, CO₂ 5.01, H₂O(+) 0.90, H₂O(-) 0.23, total 99.46%. After deduction of CaCO₃ and other impurities, MgO 53.7, B₂O₃ 46.3% against the theoretical composition MgO 53.66, B₂O₃ 46.34%. The mineral is not easily affected by cold HCl. The X-ray powder diagram of the mineral is very similar to but definitely different from, that of the artificial Mg₂B₂O₅, to which it is converted when heated up to 1, 000°C..

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