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Figure from:Chevkinite and perrierite from the Oslo region, Norway

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Fig. 2. Photomicrograph showing perrierite (black) from Bjgrkedalen, with core of loparite (grey) and pyrophanite (dark grey). The perrierite is surrounded by aegirine (grey) and microcline (light grey). (White areas are the thin section cementing material.) Length of picture 18 mm. Ito (1967), in his synthetic studies of these phases, plotted the effective size of the cations in the A posi- tion versus the average effective size of the cations in the B and C positions, and showed that the struc- ture changed from chevkinite to perrierite when the difference in these two values is excessive. Figure 3 is a plot of this kind using only synthetic materials of the type A,BC,Si,O,. which can be restated as

Figure 2 Photomicrograph showing perrierite (black) from Bjgrkedalen, with core of loparite (grey) and pyrophanite (dark grey). The perrierite is surrounded by aegirine (grey) and microcline (light grey). (White areas are the thin section cementing material.) Length of picture 18 mm. Ito (1967), in his synthetic studies of these phases, plotted the effective size of the cations in the A posi- tion versus the average effective size of the cations in the B and C positions, and showed that the struc- ture changed from chevkinite to perrierite when the difference in these two values is excessive. Figure 3 is a plot of this kind using only synthetic materials of the type A,BC,Si,O,. which can be restated as

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Fig. 1. Sketch map of the bedrock geology of the southwestern Oslo region; dots show the occurrences described in the text.
Fig. 1. Sketch map of the bedrock geology of the southwestern Oslo region; dots show the occurrences described in the text.
The four Oslo region samples (A, B, C, D) are heated in nitrogen at 1000° C for 1 hour, A = Chevkinite, Stokkoya. B = Chevkintte, Sandefjord. C = Perrierite, Bjgrkedalen. D = Chevkintte, Bjorkedalen. NH = Heated chevkintte, New Hampshtre (data from Ito, 1967). N = Unheated perrierite, Nettuno (data from Bonatti, 1959). s = strong. m = medium strong, w = weak. vw = very weak. Parenthestzed figures represent the estimated standard deviation (esd) in terms of least untts etted for the value to their immediate left, thus 100.58(12) indicates an esd of 0.12. ~~ Table 1. Observed and calculated (least squares refinements) d values and cell constants for chevkinites and perrierites
The four Oslo region samples (A, B, C, D) are heated in nitrogen at 1000° C for 1 hour, A = Chevkinite, Stokkoya. B = Chevkintte, Sandefjord. C = Perrierite, Bjgrkedalen. D = Chevkintte, Bjorkedalen. NH = Heated chevkintte, New Hampshtre (data from Ito, 1967). N = Unheated perrierite, Nettuno (data from Bonatti, 1959). s = strong. m = medium strong, w = weak. vw = very weak. Parenthestzed figures represent the estimated standard deviation (esd) in terms of least untts etted for the value to their immediate left, thus 100.58(12) indicates an esd of 0.12. ~~ Table 1. Observed and calculated (least squares refinements) d values and cell constants for chevkinites and perrierites
Table 2. Chemical composition (weight percent oxides), structural formulas on the basis of 13 cations, and measured densities (g/cm*) of chevkinites and perrierite from the Oslo region
Table 2. Chemical composition (weight percent oxides), structural formulas on the basis of 13 cations, and measured densities (g/cm*) of chevkinites and perrierite from the Oslo region
Fig. 3. Distribution of synthetic perrierites and chevkinites (Ito, 1967) as a function of the average ionic radii of the A and B + C positions. Circles: chevkinites; crosses: perrierites; circled crosses: both phases. Arrow: oxidation of a chevkinite containing Ce and Fe will cause a compositional shift towards or into the perrierite field,
Fig. 3. Distribution of synthetic perrierites and chevkinites (Ito, 1967) as a function of the average ionic radii of the A and B + C positions. Circles: chevkinites; crosses: perrierites; circled crosses: both phases. Arrow: oxidation of a chevkinite containing Ce and Fe will cause a compositional shift towards or into the perrierite field,
Fig. 4. Distribution of natural perrierites and chevkinites as a function of the average ionic radii of the A and B + C positions. Circles: chevkinites; crosses: perrierites; circled crosses: chevkinite — perrierite on heating in air. Plots A-D (Oslo region) this work, Table 2, Fe?*/Fe** chosen as 3/1; plots E (Madagascar), G (II’menskie Mts., U.S.S.R.), I (Italy) after Vlasov (1966); plots F (New Hampshire), H (Korea), J (Virginia), K (Japan) after Jaffe et al. (1956); plot L (Arizona) after Kauffman and Jaffe (1946).
Fig. 4. Distribution of natural perrierites and chevkinites as a function of the average ionic radii of the A and B + C positions. Circles: chevkinites; crosses: perrierites; circled crosses: chevkinite — perrierite on heating in air. Plots A-D (Oslo region) this work, Table 2, Fe?*/Fe** chosen as 3/1; plots E (Madagascar), G (II’menskie Mts., U.S.S.R.), I (Italy) after Vlasov (1966); plots F (New Hampshire), H (Korea), J (Virginia), K (Japan) after Jaffe et al. (1956); plot L (Arizona) after Kauffman and Jaffe (1946).