Does Buddhism view mind phenomena as chemical or as supernatural?

Does Buddhism view mind phenomena as chemical or as supernatural?

Neither. Buddhism views mind phenomena as relational. Mind is interplay of information - a transient flow of appearances arising from structures and relationships occurring between the ever changing forms (sankharas - transient conditionally existing assemblies of various factors). If you see it as such, mind is the other form of matter organization, it's dynamic side, it's structure and potentiality as it plays out over time. So the mind, strictly speaking does not require chemical basis, but it does always require some kind of media for information to ride upon.

Buddhism calls the physical 'material' ('rupa') and the mental 'immaterial' ('arupa') however it also states mind-&-body ('nama-rupa') are dependent upon eachother (refer to Nalakalapiyo Sutta).

Buddhism states the arising of consciousness without a physical body & sense organs is impossible (Upaya Sutta; Mahatanhasankhaya Sutta; etc).

It is likely mentality arises from the physical, as your scientific friends say, since when brain injury occurs, mental impairment follows.

I like the following quote attributed to (Gnostic) Jesus:

(29) Jesus said, "If the flesh came into being because of spirit (consciousness), it is a wonder. But if spirit (consciousness) came into being because of the body, it is a wonder of wonders. Indeed, I am amazed at how this great wealth has made its home in this poverty."

Gospel of Thomas

To conclude, the mind or enlightenment does require a chemical basis, which is why edible food is a requisite of the path. Without physical food, the functioning of the mind is impossible.

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.

Consciousness (viññana) and Materiality (rūpa) are related as are magnetism and electricity. Their relationship is reciprocal, each conditioning the other. They are dependently originated, i.e. neither exists independently.