Minerals of Earth's Crust for Dummies

sulfide minerals

It's common for our staffers to come across freelance posts that sort of remind us of cheese popcorn. We mean that the posts contain kernels of fact that are liberally dusted with inaccuracy... get it? Anyway, one of the kids was browsing the geology section and came across a reference to a Sciencing.com post that pretty well fits that description. Have a look at "What Minerals Make Up the Earth's Crust," as concocted by Jennifer Hayes.

The enormous and sometimes misleading images in the post notwithstanding, Hayes laid out a fairly convincing list of mineral types, replete with statistics and definitions. It's in those details, though, that the paucity of STEM classes on Jennifer's arts curriculum reared its scientifically illiterate head. For instance, Jenny told us that,

"Although similar to rocks, minerals are the building blocks for making rocks, and are found in various types of rock in differing shapes and chemical compositions..."

...which is nice padding but doesn't make much sense. Perhaps had she said, "different proportions," it would have made more sense. And then there's,

"Quartz, also called silicon dioxide, contains silicon and oxygen..."

...which would have made more sense as "contains only..." Or the line that said,

"Composed of calcium and carbon, calcite is another major contributor to the Earth’s crust..."

The compound of calcium and carbon is calcium carbide (CaC₂), not calcite (CaCO₃). Calcium carbide is unknown as a naturally-occurring mineral. Next, we find Hayes chirping that,

"A polymorph is a mineral with an identical chemical composition, but formed in a different shape."

Ummm, no, a polymorph has the same composition but a different crystal structure. Oh, and "crystal structure" is not the same thing as "shape." Moving right along, Jennifer would have us know that,

"Making up 3 percent of the crust, magnetite is black with a dull to metallic luster."

At least she got the luster right... but comprising 3 percent of the Earth's crust? Bullshit! Could it be that she meant iron oxides (hematite, limonite, goethite...) make up 3 percent of the crust?

"Found mostly in igneous, or volcanic, rock, sulfides are generally metallic and opaque, such as argentite, a silver sulfide. However, transparent sulfides do exist, including cinnabar, a mineral composed of mercury and sulfur, and realgar, composed of arsenic and sulfur."

That's her takeaway about sulfides? That there are some that are transparent (actually, they're translucent, but that distinction is probably too much to expect). Argentite? How about pyrite? And dear Lord, will someone please tell this woman that volcanic and igneous aren't the same thing?

With a list of shortcomings like that, it's no wonder that Hayes and her little post are proud recipients of today's Dumbass of the Day award. Feh.

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