Those old "Time-Life" coffeetable books are
are sooooo compelling...
I 'm not a geologist, but in the book it mentioned
the "acid igneous rocks":
Granites & quartz porphyry were listed as the two primary groups.

But what struck me was the use of the word, "acid".
We now know that acidic activity and igneous extrusions and intrusions
were common in the martian lithosphere many gigayears ago.
That being the case...
What are the chances of pegmatite rocks containing large well-formed
crystals of quartz or mica existing on Mars today? And rarer associated
minerals: topaz, sapphires, rubys, beryl, aquamarine?