First of all, "mind" here cannot be directly replaced by one Buddhist terminology. We are trying to get sensible knowledge from two different systems, literally, a goat's respiratory activity with an orange's.
where the seven aspects of perception on materiality are considered to be the combination of natural elements
I haven't read A Manual of the Excellent Man, "natural elements" here I assumed you mean chemicals. If these chemicals are pulled together, without the "man", can they think, i.e., inject these chemicals into a sole brain, or a highly sophisticated robot? Thus mind is definitely not chemical, although chemicals activities may relate to the process of thinking.
Second, Buddhist doesn't view material as "material", like the science way of material formed by atom, atom combined by electron and proton... baron, quark... etc. Material appears because the "Aware" (覺) stagnated (attached), combined by collected "logos" (names) stored in the 8th vijnana. Buddha used a metaphor in Surangama Sutra, that someone who looked at the empty space for long long time and worn out, he started to see "flowers" (sparkles of lights etc.) in the sky. Because of habitual in many many lives, this "material" interacted with us, like it has it's own property. Like someone walking on a path with a hole on it, after many many times, he gets used to the hole as if it's flat, if this hole leveled, he may feel like to walk on a mound in the beginning. The hollow, flatness is not the property (permanent, self-existed) of the hole, neither the mound.
Third, there is nothing "supernatural" in Buddhist teaching. All phenomena is as-is, including sometimes we read in the Sutras describing the abhiññā demonstrated by some arahants. "Supernatural" if we used this term is just because we don't understand how it happened.
Does Buddhism view mind phenomena as chemical or as supernatural?
Thus this is not a correct way to phase the question. I noticed "mind" is used widely in English discussion on Buddhism. This seems a confusing translation that often "mind" being viewed as the ultimate essence. Therefore, we have the term "mindfulness" to be praised and worked hard on. This is not, although I'm also in the process of learning can't be sure if I'm correct, as much as I've understood and learnt.