Some mountains generate with very little stone, as shown in the photo. This is on a default world type.

Example 1: (Jagged peaks)

Seed: 34752912104976, Coords: 43, 192, -20

Example 2: (Stony peaks)

Seed: 868565863016403259, Coords: -89, 117, 181

Steps to Reproduce:
1. Load up a new world
2. Find a mountain biome (Preferably jagged or stony peaks)                    

Observed Results:
After a few tries a mountain generating incorrectly (Like in the pictures provided) may be seen. The mountain has almost all of its blocks missing.

Expected Results:

The mountain should generate like normal.