I added 5g of elemental zinc metal powder to an acidic solution, I then proceeded to basify.

Then white emulsions form up the side of the jar and rise quickly (like soda bubbles) to the naphtha layer and sit on top of the naphtha layer.

I was getting excited because I thought that was the DMT precipitating but nope. Naphtha does contain DMT.

Any thoughts on what this could be?

It is the zinc by-products that are formed during the reduction step, they precipitate by basing. Some study is awaiting you

Tip: when you use ammonia as a base to pH 10.5 then your problem is solved. During basing you will see first the zinc salts making a milky impression, then magically disappear (oh yeah) towards pH 9 and then you'll notice a second milk appearing beyond pH 9 which are your freebased alkaloids.

As a matter of fact I've a vial just like that standing, waiting to be pulled, but then again I thought why not let it stand for a week and see if the crystals go grow on each other and lo and behold, they do. It looks like I don't have to pull with a non polar solvent anymore? Just a filter? That is sure what I'm gonna check out.