Three cabinets full of rocks. In one, metallic grains and the gray mineral enstatite; in the second, the same grains but with rusty streaks; in the third, layered clays swollen with water. All three sets were retrieved from meteorites that fell to Earth, the chondrites. They were born in the same gas-and-dust disk around the young Sun, yet somehow turned out so different. Previously, the thinking was that the disk had regions with different amounts of oxygen. The new model says: the gas was the same everywhere, it just cooled at different rates.

The authors built a numerical code, KineCond, that tracks every step of condensation: how solid particles fall out of hot gas (from 2000 down to 130 kelvins). Gas-phase reactions are kept in equilibrium, while gas–grain reactions proceed kinetically, meaning with real rates, without assuming instantaneous equilibrium. Pressure was varied from $10^{-9}$ to $10^{-2}$ bar, and cooling time from 0.01 to 1000 years. The result was unexpected: the condensation sequence did not change smoothly but split into three sharply distinct types of mineralogies. Type A (high pressure, slow cooling) resembles enstatite chondrites: metallic iron and enstatite, no oxidized iron. Type C (low pressure, fast cooling) yields oxidized phases, fayalite, magnetite, troilite, phyllosilicates, coexisting with high-temperature CAI minerals. Type B is transitional, with metal, troilite, and fayalite.

The three cabinets of rocks turned out not to be different kitchens but one recipe with different cooking times. Slow fire, and the pot holds metal without rust. Fast fire, and the same pot gets covered in clay and rust. Medium fire, a mix of both. The gas in the disk was one, but it cooled differently in different places. Thus local conditions produced all the diversity of chondrites.