Geologist needed (or people who are just smarter then me)

Hi all,

I’m proof reading a book that one of my friends wrote. In it he has an object that I don’t believe could stand up to scientific scrutiny. It is a Diamond that naturally formed around a Ruby. What I’m interested in is if it is impossible or improbable. If it’s impossible he will want to change it, if it’s improbable he can say that it’s very very rare and keep it.

A second question that I have is what are Rubies made from? We all know that Diamonds are created from carbon under high heat and pressure, but what is the base element and growing conditions for Rubies?

Thanks in advance

Composition of Rubies:

Gems are not my area of expertise. However, it doesn’t seem very likely to me at all, because diamonds and rubies form in different geologic settings. Diamonds are associated with with dark, mafic (high iron-magnesium) rocks such as peridotite and kimberlite, which typically form in high-temperature, high pressure settings. Rubies, on the other hand, are associated with several rock types - nepheline syenite pegmatites, gneisses and hornfels in metamorphic terranes - that are generally light-colored and felsic (poor in iron and magnesium, rich in feldspar), and may form at high temperatures but under a range of pressures. The crystallization conditions for diamonds and rubies are pretty different - I can’t envision being able to switch from one to another in a natural setting.

“Ruby” refers to red forms of the mineral corundum, which is aluminum oxide (Al[sub]2[/sub]O[sub]3[/sub]). Any other color variety of corundum is called a sapphire.

Sounds like your friend has misidentified the minerals in his sample, if it is in fact genuine and not manufactured. How did he arrive at his ID?

I’m sorry for the Confusion I guess I should have been more specific. My friend wrote a fictional book in which the main characters are looking for this artifact. It is in no way a real. I’m just curious if it is Possible, even remotely. Thanks for all the help so far.

Ahh, that does clear things up. I would say that it’s not possible to have such an item in natural form. If your friend really likes the idea of having it in his novel, then he could keep it & chalk it up to poetic license. Reading novels with some sort of a geological angle is a hobby of mine (surprise! :wink: ), and I can tell you that pretty much every author has made at least some minor errors in describing rock types, geologic formations/settings, etc. All-time worst offender I’ve encountered so far: Clive Cussler’s Atlantis.

Pretty much what Fillet said. The bottom line is, it is very highly improbable–and only because I hesitate to use the word impossible.

From a naturalist perspective, it’s never been observed in nature. From a physio-chemical perspective, it’s thermodynamically improbable.

Plus, if the diamond formed around the ruby, then the ruby formed first and the diamond crystallized around that. How could that happen? A ruby would have to crystallize from an Al-rich melt (or during metamorphism of Al-rich sedimentary rock). The ruby-bearing rock would then have to be subducted into the mantle (which would be hard to do, considering Al-rich rock has pretty low density) where it’d be expected to survive both the high-PT conditions AND the carbonate metasomatism required to from diamond. Call that sequence of events Geologically improbable.