Very good indeed, now we are having some fun exploring this fascinating plate.

What Johan mentioned, figures 49-52, were indeed 'copied' or matched, to figs. 1-5 of Steno's De Solido, 1669 (please see attached). This happened on occasion for a number of titles. For example, figures from  De Boodt's Gemmarum et Lapidum, 1609, are seen in a number of other publications, copied. Diderot's Encyclopedie, as another example, draws from numerous older editions for many of their illustrations, for the section that covers mining, mineralogy, &c.; drawing on Hooke, Leigh, Loehneyss, &c., &c. 

Hrmm, it won't be a plate from the 1922 ed., that plate looks contemporary, the paper. Also, it is tipped in, just as many plates were in those days.

It is an educated guess only, that it might be from another work/article by Cappeller, on account of the similarity of the plates; or, perhaps he had intended to expand on the work, and that plate had been prepared for it, but no more was issued. 

Hrmm, very good indeed, fascinating, how I read that (so far) it would appear that the manuscript for the work, was longer than the Prodromus, and that it included data on quartz. When the Prodromus was issued, the section on quartz was not included. However, some material had been printed (presumably, that dealing with qtz), but was not included, or removed prior to issue. Possibly, the plate for that section was also printed (yours here), and that did make it in to some copies. The extra leaves were removed from all copies (as far as we know; it'd be interesting if copies exist, where those leaves had not been removed), and some copies retained the plate. A fascinating issue, this Prodromus. 

It ought be remembered that a prodromus is an 'introduction' to a far larger work (the base of which was that manuscript). As they printed the prodromus, they changed their mind, they had intended on including the section on qtz, but did not do so for some reason. Some material was printed, but it was not included/removed, as the prodromus was set. But, the plate to that section, also ready, did made it into some copies. As I guess it, so far.

I thought you owned that copy - lucky bugger! I thought.

Oh, question, the other plates are tipped in the exact same fashion? Onto blank leaves, folding?

 Keith,

Och... ;)