I was fascinated to discover that Australian Bauxite had been investigating bauxite deposits near Guyra. You can find the company's press release here.
The map shows the drill hole locations, with thick, high grade bauxite marked in red.
It appears that the bauxite includes some exceptionally high grade, thick gibbsite bauxite suitable for use as a sweetner in bauxite refining.
Apparently, you mix the high grade with lower grade bauxite to accelerate the refining process.
You can see that the new discoveries are close to the now disused Great Northern Railway. The suggestion is that bauxite mining might support the re-opening of this portion of the line.