Yugawaralite

Figure 1.74. Zonal sequence of the propylitic alteration in E-W section of the Seigoshi-Toi mine area (Yug = yugawaralite Heu = heulandite Stil = stilbite Opx = orthopyroxene Mont = montmorillonite Mor = mordenite Lm = laumontite Wr = wairakite Chi = chlorite pr = prehnite ep = epidote Py = pyrite Kf = K-feldspar Cpx = clinopyroxene) (Shikazono, 1985a).

The eoexistence of laumontite and wairakite is common in zone (1). If the saturated water vapor pressure is equal to 0.3 of total pressure (Zeng and Liou, 1982), the temperature for equilibrium reaetion (1—23) and saturated water vapor pressure are estimated to be 170°C and 230 bar, respectively (Liou, 1971b). Zeng and Liou (1982) have shown that yugawaralite is stable at less than 230°C and a total pressure of 500 bar, under the condition of quartz saturation. However, if the activity of Si02 is not unity, the boundary for reactions (1-24) and (1-25) may shift to lower temperatures. Liou (1971a) studied the equilibrium for reaetion (1-26) and showed that the equilibrium... 

Zeng, Y. and Lion, J.G. (1982) Experimental investigation of yugawaralite-wairakite equilibrium. Am. Mineral, SI, 937-943. 

A catalogue of zeolites commonly considered to be ordered is shown in Table 1. It is to be noted that the real symmetry is always lower than the topological symmetry, with the exception of laumontite. A low Si/Al ratio seems to favour order, but in goosecreekite and in yugawaralite, two of the most ordered zeolites, the Si/Al ratio is as high as 3. 

In the citse of high Si/Al ratio, order is favoured by the presence of divalent medium size cations (e.g. Ca). Wairakite and laumontite, with Si/Al=2, and goosecreekite and yugawaralite, with Si/Al=3, are Ca-rich zeolites. 

YUG Yugawaralite Ca2[Al4Sii2032]-8H20 Yugawara Hot Springs (Kanagawa Prefecture, Honshu, Japan)... 

Not all zeolites fit neatly into any simple classification. In yugawaralite, Ca2Al4Sii 2O32.8 H2O, there is a 3D framework consisting of 4-, 5-, and 8-membered rings in which the widest tunnels form a 2D system (being parallel to the a and c axes) but there are also smaller channels parallel to the b axis. ... 

The basic structures of nearly all of the zeolite minerals appear to have been resolved, including the complex structures of laumontite (17), stilbite (39), heulandite (63), and yugawaralite (55). In addition, the relationship of the zeolites erionite and offretite has been delineated further by the work of Kawahara (51) and, in this symposium, by Gard. Zeolite minerals for which structural analyses have not been completed include the widely occurring mineral clinoptilolite and the rarer mineral stellerite, which apparently is related to stilbite. 

The mineralogy of yugawaralite (42), gonnardite (41), stilbite (43), ferrierite (2), offretite and erionite (70), and faujasite (50), have been reported. 

Stilbite Barrerite, stilbite, stellerite, thomsonite, tsehemichite, yugawaralite Monoclinic... 

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