How do i create a significantly correct world with large crystal formations in my novel?
Do you mind a scenario somewhat less dramatic than exploding suns? ;)


Just let selenite ($\ce{CaSO4*2H2O}$) cristallize very slowly und undisturbed in a system of caves for a long time. 
Let the inhabitants of your world discover the cave system or let parts of the cave system collape to make it more accessible.


A model for this already exists: the Cave of the Crystals, connected to the Naica mine in Mexico.



Update

Note that I'm not a geoscientist, but to me, large hexagonal columns that can exist under earth's atmosphere cry basalt, which in turn indicates vulcanic activities.

The English wikipedia has a list columnar structures resulting from vulcanism. Some examples are


Giant's Causeway in Northern Ireland
Fingal's Cave in Scotland
Devil's Postpile in California