Hacker News Reader

Comment by cbkeller | Hacker News Reader

Geologist here. Can't speak to the economics, but there's no shortage of mineable olivine, mostly in areas where mantle lithosphere that was formerly below oceanic or island arc crust has been "obducted" on the continental crust and thrust up to the surface (the mantle is mostly olivine). These are called ophiolites, and they're not uncommon in places where you used to have a destructive plate boundary: https://en.wikipedia.org/wiki/Ophiolite

View on HN

Hi! You are correct in how common it is. We will be utilizing forsterite (MgSi4O2), the magnesium-rich form of olivine. We are looking to mine large dunite massifs as they are more than 90% olivine and close to the surface. And you are also correct in that these type of deposits are usually found at the base of the ophiolite sequences. :)

If you are interested in getting involved, feel free to msg me!

Happy to help if my expertise becomes relevant

Google says there’s 2.996×10^12 tons of carbon in the atmosphere. I’m guestimating we have about 1/3 of that which needs to be pulled out to correct for emissions to this point. Do we have access to that amount of olivine?

Thank you so much for your comment!

Edit-As to pricing, if olivine is a common byproduct of other activities and generally common in that sense then obtaining 1 ton of olivine is the cost to move it. Then they need to process and disburse it. That seems like a cheap process.

Edit2-the non-cheap part of this seems the dispersal. How long will it take to disperse all that olivine?

> I’m guestimating we have about 1/3 of that which needs to be pulled out to correct for emissions to this point.

For the moment, that’s a slight overestimate; we’re a little over 400ppm, and pre-Industrial levels were about 300ppm, so we “only” need to remove 1/4 (and we don’t really need to go back all the way to preindustrial levels, it was about 325ppm in 1970)

With 20/ton of olivine it’s still around a 20 trillion dollar industry (just that cost alone)!

Yes! Just to pick one famous ophiolite, the peridotites of the Semail ophiolite in Oman are perhaps 300km * 50km * 5km from a quick look at some maps and cross sections [1], so 75000 km3 at 3300 kg/m3 comes out to about 2.5E17 kg or 2.5 E14 metric tons. So that's just one ophiolite and we've got a few orders of magnitude to spare.

If for any reason ophiolites weren't enough, there's places at slow-spreading ridges where it's peridotite all the way from the ocean floor to the outer core, albeit expensive to mine.

In short, we would run out of CO2 before we run out of olivine.

[1] https://doi.org/10.1144/gsjgs.151.3.0555

Reply on news.ycombinator.com