What does dendritic mean in mineralogy ?

Dendritic : definition

Dendritic means a growth in the form of a tree, with branched lines, which can apply to crystalline buildings but also to roots or branches.

Pyrolusite and native metals (gold, silver, copper) commonly form aggregates exhibiting this dendritic growth. During this growth, the tops of a crystal develop more rapidly than the faces which then appear hollow, one then speaks of skeletal facies.

The photo on the right shows manganese dendrites (pyrolusite) on limestone.