Stalactite and stalagmite are pointy, pillar-like structures formed within caves with time. These formations are due to the activities of many different types of minerals that might be present within caves.
But this calcium bicarbonate is present in the roof of the cave. And it becomes easier for small mineral deposits to fall onto the ground.
It helps in initiating the formation of stalagmite.
But the main thing about stalagmite formation is the volume or the partial pressure of calcium carbonate matter.
It should be greater than that of carbon dioxide to form the calcium bicarbonate and further stalagmite.
It is easier to form stalagmite because of constant dripping falling off the roof from many different areas.
When made up of minerals from lava formations, they tend to be really hard and sometimes hazardous.
References
- https://aip.scitation.org/doi/abs/10.1063/1.2006027
- https://www.sciencedirect.com/science/article/pii/S0012821X03003698