Those People Hiding Mineral Make A Scientific Statement

[Turra]

Finnies

[Toorak]

Theorem

[Baldric]

From the page header

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[Tuvok]

Finnies? Finnies the Jeweller?

[Mamyalynne]

Yes, I presume the sponsor the crossword in some way.

Press & Journal.

[fiction-factory]

More info given in the follow-up thread
https://www.theanswerbank.co.uk/Quizzes-and-Puzzles/Crosswords/Question1650286.html