At nearly 1 foot tall, this is an amazing example of how the colours of minerals will change as the mineral crystallized.
The different colours form as the mineralogy changed as the fluid crystalizes.
This happens as some elements will preferentially crystallize first, leaving the crystal fluid richer in the remaining elements, that cause the tourmaline to have different 'layers' of colours.
Tourmaline is usually black in colour & common throughout the W.A. GOLDFIELDS, mostly associated with Quartz Veining. This will often look like black veining within the quartz that will generally make that part of the quartz vein much harder and more resistant to weathering, which is why it can often be found as pieces of quartz 'float' scattered on the surface..... and YES, can be an EXCELLENT indication that gold can be associated in the nearby area as this tourmaline-quartz veining is a good sign that the area has had several generations of faulting associated with hot fluids.
So tourmaline does not guarantee that there will be gold-bearing quartz veining in the area, but seeing these rocks does make your chances 'better'.
Hope you like this rare example, one of my favourite minerals.