In my first post about using minerals, crystals, and stones in ways that correspond to the chakras, I specifically left out any discussion of clear/white and dark/black stones. In thinking about the expanded chakra system the role of these stones becomes clearer: dark and black stones will draw energy and awareness down into the ancestral chakra and act as grounding stones, while white or clear stones will draw one up into the transpersonal chakra. This makes sense given the general perception that black or dark stones are grounding and clear stones are good for directing energy. [*]
The real question here is whether one chooses to see the crown chakra as white. That means collapsing light blue and dark blue, or blue and indigo, together into the throat chakra and attributing purple to the third eye chakra. (That system – with only one blue – has a lot to recommend it also!) If you see the crown chakra as white, then it could make sense to attribute white but cloudy stones to the crown and truly transparent stones to the transpersonal chakra. As with all correspondences, your practice will vary depending on multitudinous factors.
Regardless of the exact attributions, I have found that selenite, clear quartz, white or clear calcite or fluorite, and similar stones are definitely good for expanding one’s energy and awareness up towards the transcendent. Selenite in particular is a gentle mineral for this type of work and is very good for directing Reiki energy.
On the dark/black end of things, it makes sense that black tourmaline, jet, obsidian, and similar stones are good for grounding. These dark or black stones are also useful for drawing out or off any excesses or negativity that have been picked up, just as it is useful in grounding to let go of such things and let the earth take them in and “recycle” them. Another way to think of this is that these stones’ connection to the ancestral chakra serves as a way to take that energy back into the void or the collective unconscious. (Honestly, I’m still exploring the exact terminology I want to use around these concepts, so I’m interested in how others see this also!) Of course, a stone from one’s own landbase is also an excellent stone for grounding!
With these things in mind, it’s worth noting that tourmalinated quartz combines these qualities, so it is most useful for seeking balance, especially balance between the immanent and transcendent. Smoky quartz can do something similar, although it has plenty of other specific uses of its own, and snowflake obsidian can also work for balance although with an emphasis on grounding.
* Actually, the idea that “energy” must be white or light is an interesting bias in our metaphysical ideas. It shows that we tend to think of this energy as coming from the above, the transcendent, as those are connected with what is traditionally good in the dichotomy of good vs evil. This bias seems inappropriate to me because I worship the divine in everything, both the transcendent and the immanent, and because I think there’s a lot of power in the shadow, the dark, the silence, which we need to work with. But Shadow work is a whole pursuit of its own, so for here I will only note that I think clear/white and black/dark stones are equally capable of working with energy, they just do so differently.