Well, Jay, I understand your frustrations. Rocks are not simple. That is why most folks are content to just call them rocks.
Rocks are a combination, or mix, of minerals. This specimen would be called a rock because of the metal content. I don't know why your scientist friends would think the metal content is unusual? It is very common to find rocks like this with bits, or significant amounts, of metal. You may want to find a geologist to talk with also. The cubic-like shape of the 'pockets' of the dark metal in this specimen remind me of weathered Iron Pyrite but could easily be Magnetite as well. And, of course, it easily could be something else altogether?
Iron is found almost everywhere on Earth, along with other elemental metals like Manganese and Magnesium, for examples. Iron breaksdown, decomposes, morphs, or oxidizes into the mineral Magnetite, for one, and the other metallic elements contribute in the formation of many other wonderful minerals. And there are many, many different stages to this process. We amateurs have the luxury of saying things like, "Well, it's almost this, and It's almost that." But when it comes down to it, it's a rock.
All you can do is keep studying, reading, and looking at a lot of rocks. The first time you read something is just an introduction. It takes time, study of many different specimens, and several rereads for it to sink in. Which is why I like to say about this hobby; We are always learning.
You may want to start by rereading the Geology.com link for Epidote I posted in your other "More Colorful Granite" thread. Something might jump out at you that didn't the last time you read it?