Gyrolite

Hydrated calcium silicate minerals such as xonotlite, truscottite, and gyrolite are rare but have been reported from several Au-Ag deposits. They do not coexist with Au-Ag minerals but instead are found with quartz, carbonates, and johannsenite. However, in the Keisen No. 3-2 vein in the Hishikari Au-Ag deposits, a close association of electrum with truscottite, smectite and calcite is observed (Imai and Uto, 2001). 

The difference (Ca,Na)02.8H20 between the chemical compositions of reyerite and gyrolite is accounted for by the presence in gyrolite of a partially filled... 

The ideal composition of tungusite differs from that of gyrolite by the presence of six divalent cations, which complete the (001) X sheet of which the dimensions a b 9.72 A, y = 120°, thickness about 2.8 A) correspond to those of a 3 X 3 trioctahedral sheet. 

Fedorite [73] [K2(Ca5Na2)Sii603g(0H,F)2.H20 PT, a = b = 9.67, c= 12.67A, a = 102.2,13= 71.2, y = 120.0°] is also based on O and S2 modules (Figure 17-17). Reyerite, gyrolite and tungusite contain the same module OS2 that, instead, stands alone in the crystal structure of fedorite. These minerals, together with other... 

Figure 17-17. Perspective view of crystal structures of reyerite (a) gyrolite (and tungusite) (b) and fedorite (c)...

Shaw S, Henderson CMB, Clark SM (2002a) In situ synchrotron study of the kinetics, thermodynamics, and reaction mechanisms of the hydrothermal crystallization of gyrolite, Cai6Si2406o(OH)g-14H D. Am Mineral 87 533-541... 

C-S-H (I) is transformed into tobermorite only exceptionally, at low addition of Cr203. Xonotlite is formed at significantly higher temperatures. Because Cr203 does not form the sohd solution neither with xonotlite, nor with gyrolite or truscot-tite, it occurs at higher temperatures as Cr(OH)3. 

G gyrolite, X xonotlite, H hillebrandite, E ellestadite, P portlandite, A anhydrite... 

The transformation into tobermorite will be also occurring, which will have characteristic plate-morphology, sometimes as elongated crystals (Figs. 8.11 and 8.12). The formation of gyrolite and trascotite is also possible the composition of these phases is shown in Table. 4.4. 

Jull Lees (1990). The only exception to this is the work of Mchedlov-Petrosyan et al. (1968), who identified a number of crystalline C-S-H phases by XRD including hillebrandite, gyrolite, afwillite and tobermorite in an ancient mortar. The authors suggested that initially amorphous CSH gels may have altered to more crystalline phases with time. This process has been observed to occur within laboratory timescales at 90°C or more (e.g. Atkinson et al. 1995) but has not been documented at low temperatures, even over long times. 

Gyrolite, reyerite, tobermorite, truscotite. See Calcium Silicates. 

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