torama t1_j68ce7b wrote on January 28, 2023 at 1:40 PM

Reply to comment by CrustalTrudger in can gemstones be melted into a gradient? by Acceptable_Shift_247

Nice explanation. The melting point of quartz is wrong though. I used quartz reactors at above 800 C degrees.

CrustalTrudger t1_j68gvxn wrote on January 28, 2023 at 2:20 PM

Yep, corrected.

OrbitalPete t1_j6m0dr1 wrote on January 31, 2023 at 7:21 AM

OK, so forgive my lack of mineralogy but why does quartz only start dumping out of silicate melt below about 800 degrees? Is this at STP?

torama t1_j6m5nro wrote on January 31, 2023 at 8:32 AM

Sorry English is not my first language, what do you mean by "dumping out of silicate melt below"?

OrbitalPete t1_j6m8ett wrote on January 31, 2023 at 9:12 AM

You only start crystallising quartz in a silicate melt (I.e. magma) below about 800 degrees. Above that the silica only gets accommodated in other minerals.

torama t1_j6msxjm wrote on January 31, 2023 at 1:18 PM

Solubility of phases and their precipitation is not really related to their melitng points. Things can dissolve or precipitate at wildly different temeperatures.