Fluorspar

Figure 13. Summary graphs (p97 of notebook) for fl...

Figure 13. Summary graphs (p97 of notebook) for fl...

Figure 13. Summary graphs (p97 of notebook) for fluorspar, zinc blende and pyrites

Figure 13. Summary graphs (p97 of notebook) for fluorspar, zinc blende and pyrites

Fluorspar, CaF2; Zinc blende, ZnS and Pyrites, FeS2

The experimental data for these crystals is gathered together in graphical form by WLB on p97 of the notebook, the extent of the vertical lines representing the intensities of 1st, 2nd etc order reflections from the (100), (110) and (111) planes.

This data is reproduced in numerical form in Table 1 of the WLB paper, Analysis of Crystals in the X-ray Spectrometer(16), reproduced in figure 7a.

The importance of these comparisons (which also include rock-salt) is that it enabled the Braggs to deduce the atomic positions (and hence point and space group symmetries) of all these cubic crystals.