Question

Under which crustal temperature and pressure conditions will andalusite form?

a) 300°C and 6000 atmospheres
b) 500°C and 2000 atmospheres
c) 600°C and 4000 atmospheres
d) 700°C and 8000 atmospheres

Answer 1

Andalusite forms under crustal temperature and pressure conditions of 600°C and 4000 atmospheres.

Step-by-step explanation:

The correct answer is c) 600°C and 4000 atmospheres. According to the pressure-temperature diagram for aluminosilicate minerals, andalusite forms at temperatures around 600°C and pressures of approximately 4000 atmospheres. This information is depicted in Figure 2.21, which shows the stability fields for andalusite, kyanite, and sillimanite.