1. Pressure: As pressure increases, the melting point of rocks also increases. This is because the high pressure forces the molecules closer together, making it harder for them to break apart and melt. This is why rocks deep within the Earth melt at much higher temperatures than those near the surface.

2. Composition: Different minerals within a rock have different melting points. A rock with a high concentration of silica (like granite) will melt at a higher temperature than a rock with a high concentration of magnesium and iron (like basalt).

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