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Geology/Found a weird "rock" in a cave. Don't know what it is.



Other side.
Other side.  
My Husbend went into a small narrow cave on Vancouver island bc. He broke off a price of white rippled rock. Very sparkly.

Don't know what it is?

Hi Rhianna,
What you have there is called a "speleothem", more commonly called a stalactite or stalagmite.  Speleothem is a generalized term for this type of formation, normally found in caves.  

Groundwater moves through rock and, most often, carries dissolved minerals in it.  When the water drips in a cave it leaves some of the dissolved mineral behind on the cave ceiling and the cave floor beneath the drip.  Over time they can form columns and pillars.  Anything that can be dissolved in water can eventually become a speleothem but mostly they are made of calcium carbonate (usually called travertine when found in a cave).

That's what you've collected; a travertine speleothem.  If you collected it from the ceiling it's termed a stalactite and from the floor it's a stalagmite.  

GOOGLE either term and you'll find a gazillion images.  Most are larger but they still give you an idea of the variety.

Hope this helps.


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C. Robert Reszka, Jr.


I can answer any general geology question (rocks, minerals, stratigraphy, geomorphology etc.). My expertise is in the geology of the Michigan Basin, PreCambrian, Paleozoic and Recent. I can answer questions concerning mining and petroleum exploration and production and the laws concerning those activities. I can also answer questions concerning stratigraphy of the Michigan Basin. I will also answer questions about mineral and rock collecting in the Basin. I won`t be able to answer many specific questions on hydrology, geophysics or geochemistry. I may be able to answer very general questions in those venues.


I have been working for the State of Michigan for 36 years as a Geologist and a Resource Analyst. I have experience with Subsurface Geology and Petroleum Geology, mining in Michigan, and Sand Dune Mining and Protection issues.

Michigan Basin Geological Society

Decade of North American Geology.
Bedrock Geology of Michigan

BS Wayne State University

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