I want to know how hard or strong typical speleothems are. For example, could an average man break off a small stalactite or soda straw? If they're very hard, how do they compare to bone?
The speleothems are made of calcite, so breaking one small stalactite is same as breaking one narrow "straw" of calcite. Calcite is not so strong, so it is pretty easy to break small stalactite. Bone is much much stronger than one stalactite. Of course, the big ones (1 meter diameter) are harder to break.
I see that you asked this here because you don't want to try it in real life, and I approve that :)