The Black Triangle is a roughly triangle-shaped area rich in iron, mostly in the form of ironsand. It occupies part of what was the Yokto Volcanic region in the Bloodian Period. Consequently, igneous rocks and metals abound, with titanomagnetite especially common. A few foothills of the Eumenides Mounts are represented, but they are greatly reduced in stature. These foothills are now pitiful hills, the biggest of which are barely taller than a meter. Due to being rich in titanium ore, these hills possess steel-like durability.
(Black Triangle location in red)
The dark color of the sands absorbs heat. In the right conditions, some hills become so hot (130 degrees Fahrenheit, or 55 C) that eggs can be cooked on them. (Albeit in 20 minutes.) However, if Mason's atmosphere continues to dwindle, the planet will become too cold for egg-cooking.
The Black Triangle has large amounts of the following minerals: ilmenite, titanium, granite, diorite, zircon, manganese, vanadium, phosphorous, and silica.