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

Coordinates: 43, 192, -20

Example 2: (Stony peaks)

Seed: 868565863016403259

Coordinates: -89, 117, 181

Example 3: (Jagged peaks + Stony peaks)

Seed: -4680646807128482073

Coordinates: -6645, 153, 24228

Example 4: (Jagged peaks)

Seed: 1124678029

Coordinates: -185, 207, -10

Example 5: (Jagged peaks)

Seed: 1050958664

Coordinates: -27, 207, 10

Steps to Reproduce:
1. Load up a new world
2. Find a mountain biome (Preferably jagged peaks but also 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. I've tried it with many mountains and this bug seems to affect 1 in 5 jagged/stony peak mountains.

Expected Results:

The mountain should generate normally.