#peridotite

yes!! here's a jason comic. on the next page he was gonna be disappointed that it was human food but i never drew that bit

Hey, peridotite! Apologies for the late reply!

Wow, getting a thesis topic is so exciting! If you’re anything like us, you’ll absolutely fall in love with your study subject. And migmatites make it easy - they’re such beautiful and fascinating rocks! That is a VERY cool photo, too. It shows off those wonderful warped folds perfectly ::)

As for the Eye’s surface, we had the same thoughts as you! The warped, irregular folds, not following typical folding patterns, definitely reminded us of partial melting like you see in migmatites. The oldest rocks on Earth are metamorphics - after being around for so long, they have inevitably been subjected to alteration by high temperatures and pressures. Metamorphics are durable, and high-degree metamorphics like migmatites can be protected from erosion and surface degradation since they form so deep in the crust.

There are a few other features of these rocks that made us hesitant to class them as metamorphics right off the bat. Firstly, that very glassy sheen they can have. This is more reminiscent of an igneous rock to us, although metamorphics can certainly be shiny. Additionally, they are FULL of holes - very Swiss-cheesey rocks haha. These could be present for a variety of reasons, such as them being now-exposed vesicles in the rocks, or conchoidal fracturing, or perhaps void cavities where another mineral once laid and has since become dislodged or eroded out. These features are more likely to point towards an igneous rock than a metamorphic, or a volcanic glass, such as rainbow obsidian (which matches the lustre, fracturing patterns, and colourful striping of quantum rocks!).

Fig. 1: Unpolished rainbow obsidian from California. Note the conchoidal fracturing, smooth sheen, and coloured bands!

With that said, we definitely lean towards it being some kind of metamorphic. Its apparent longevity certainly lends itself to the theory that it’s a metamorphic, and it would be very fitting for the oldest thing in the universe to wear its age and all that it’s weathered throughout the millennia on its surface. And, of course, the actual surface of the Eye lacks the sheen and hole-y appearance the more elevated rocks exhibit, so perhaps we are looking at two similar but separate rocks here!

Fig. 2: The Eye as it appears on the Quantum Moon. Despite appearing at first glance to be made of homogenous materials, the surface lacks the glassy sheen, vesicles, and broad banding of the quantum rocks above the surface. We could be looking at two separate (yet similar) rock types!

Thanks so much for the ask! This is definitely a topic we’re still working through for the official survey, and the migmatite comparison is a fantastic one. We wish you the best of luck on your thesis (and that the migmatites treat you well)!

Monte Duria Peridotite

Today's Specimen: Peridotite

Peridotite, not to be confused with Peridot, it's gemstone variety, is a rock rich with Pyroxene and Olivine, which is the material Peridot comes from (the gem form of Olivine). Peridotite is ultramafic (containing high magnesium and iron, but is low in silica) and coarse, and makes up a significant part of the Earth's mantle. This funky rock is an essential source of iron, nickel, talc, chromium, cobalt, peridot, garnets, and even diamonds! It has a hardness of 5.5-6.0 on the Mohs hardness scale, depending on type. Types of Peridotite include: Harzburgite (contains orthopyroxene), Lherzolite (contains orthopyroxene and clinopyroxene), Wherlite (contains clinopyroxene), and Dunite (contains over 90% olivine).