Carbonatite for the Dummy Geology Student (WiseGeek Week 4)

Considering how often people seem to make fun of geology and geologists (think Bert on "Big Bang Theory," or the introductory course everyone calls "Rocks for Jocks"), you might think that it's so simple even a child knows everything about it. You would, of course, be wrong: it's really not that simple... even if some "creative writing" graduate like Andrew Kirmayer thinks it is! Want proof? You need look no further than Kirmayer's WiseGeek.com post titled "What is Carbonatite?" (now at niche site AllThingsNature.com).

Having actually seen a carbonatite near Hot Springs National Park in Arkansas, USA, our staff geologist could rattle off a quick definition: "Carbonatite is an igneous rock composed mainly of carbonate minerals." Sadly, that's at odds with Andrew's daffynition, which is,

"Carbonatite is a form of volcanic rock that typically has various minerals embedded within it. "

Well, hell, Andrew: igneous and volcanic aren't the same thing, and all igneous rocks¹ have "various minerals embedded within" them! For that matter, damned near all rocks have "various minerals embedded within" them! Kirmayer, however, is not finished exposing his scientific illiteracy. No, there's more:

"Minerals such as iron, barium, calcite, and dolomite are often seen in carbonatite. Small amounts of uranium, titanium, or phosphorus are sometimes contained within it as well."

Iron and barium aren't minerals, Andrew, they're elements. And to say that "calcite [and] dolomite are often seen in carbonatite" is rather inane, since calcite and dolomite are the most common carbonate minerals found in carbonatites! Sheesh!

Kirmayer continues his self-flagellation, mostly in a general discussion of igneous rocks and of the rock cycle in general:

"Lava that flows out onto the surface or molten rock that intrudes into materials underground can form carbonatite... Extrusive igneous rocks, which typically erupt or flow onto the surface, can contain carbonatite. These typically melt at relatively low temperatures or become a powder-like material that gets blown away by the wind or washed away by rain or flowing water." 

We think he's talking about metamorphism, weathering, and erosion... but who knows?

What our staffers found most bizarre about Kirmayer's carbonatite post is that we couldn't find any reference that defines carbonatites without stating the mineralogy, e.g., Mindat's definition, "An igneous rock containing more than 50% modal primary carbonate." Yet Andrew never once mentioned this definition, instead further supidifying the internet with his half-assed rewording of general information about igneous rocks. That's classic Dumbass of the Day work, Andrew...

¹ We suppose you could exclude volcanic glass – obsidian and pumice – from that "all"

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