Geology And Geophysics

Difference between Pumice and Cinder

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"Difference between Pumice and Cinder"
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Have you ever put volcanic lava in your mouth? You may be surprised to find out that if you've ever brushed your teeth you may have. Volcanic rocks like Cinder and Pumice are used everyday in many ways, form the roads people drive on, to the jeans they wear.

Both cinder, also known as scoria, and pumice are formed during pyroclastic episodes, when a volcano violently ejects magma from it's core. It can be difficult for an average person to tell the difference between these igneous rock formations. They share many similar characteristics, including some color similarities, weight, and density.

There are however, a few ways you can differentiate the two rocks with the naked eye, and one if you have a water source.


With color, cinder generally assumes three shades, red, black, and brown. While pumice can also have a brown or black shade, if you are seeing something that is white, cream, bluish grey, or green, you are dealing with pumice.

Another difference that can be seen is the size of the vesicles, or holes in the rocks. Pumice has many, many tiny holes on it's surface and the finish of Pumice is like glass. Cinder also shares this characteristic but the holes tend to be larger, most measuring more than 2 millimeters in length or width and because of this cinder is rough and very porous.

Composition and Density

The water test has to do with the specific gravity. While both rocks have a very low density, pumice floats on water in almost all occasions, while cinder will sink, as it's density is greater than water.

Composition wise, cinder tends to have a higher amount of basalt, which is a very hard stone. Pumice has almost no crystal composition and is essentially composed of silica or glass structures.

How we use them

As to uses of each rock, cinder provides great traction on road surfaces in wet and icy weather. Because it is so porous it is also used in gardening. You find it in construction in cinder blocks.

Pumice has more versatile uses. It is essentially a glass, and is often found as an abrasive additive to soaps, toothpastes, cleaners, and as an additive to concrete. It's also found in many cosmetic applications like stones for callus removal and skin exfoliation. It's also used in washing blue jeans to create a wear effect.

Both rocks have a place in society and are great examples of natural elements for industrial uses.

More about this author: Todd Hendrickson

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