I set the world generation to "buffet" mode and made the biome soulsand valley. I found some bones on top of a basalt pillar.
MC-172391
In a soulsand valley, bones can spawn on basalt pillars
Resolved
Duplicate
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David Richardson
(Unassigned)
Unconfirmed
(Unassigned)
20w07a
Retrieved
Duplicate of MC-171491 - as they spawn at the same y level, so it's just rare that a basalt generated there.