what kind of rocks are used on the railroad and can some of them float?

Answer 1

Many types of rock are used as ballast on the railroads, granite is very common as is scoria of various types. Volcanic scoria often has pumice associated with it, and particularly on the Burlington Northern (now BNSF) it was not uncommon to find some pumice (which floats) along the tracks in the 1980's. Obsidian and basalt that was obviously from a lava flow were also common in that ballast. I believe that ballast came from quarries in Washington state or Montana. Since railroads usually don't remove old ballast and just add new on top, the ballast with the pumice in it is still there, but most of it will be covered unless they are still getting some pumice mixed in along with the better ballast rock or the roadbed has been disturbed, bringing out the older layers of ballast..

Primarily, ballast needs to be made from a rough rock that drains water easily, "locks" together well so it doesn't move around and let a train derail, and it has to be durable if it's on a line with much traffic so it doesn't break down as quickly under the weight of passing trains. That's why pumice isn't very good for ballast, it crushes too easily. For shipping cost purposes, they usually try to get rock from a source in the same part of the country if it's available and not signifigantly higher in price per ton. One quarry that has been a very prolific producer for the Union Pacific and many other railroads is the Sherman Quarry just west of Cheyenne Wyoming, which provides stone from the 1.4 billion year old Sherman Granite Formation. Missile Base pit west of Spokane Washington and another quarry near Castle Rock Washington also provide large quantities of ballast, but I'm not sure exactly what type of rock it is. In the Midwest, quarztite is sometime used from quarries in Minnesota, and on some sidings and seldom used tracks softer rock like limestone is used much of the time.

Answer 2

Railroad Ballast Rock

Answer 3

I'm not really sure what you are asking.
by "on the railroad" do you mean the gravel, broken up pieces that are under the wooden rail road ties to level and stabalize the tracks? i've seen lots of basalt, but also lots of any local rock is used.
A rock that can float is pumice, a frothy extrusive igneous rock. I've never seen it used in any kind of railroad application though.

Answer 4

Classic Rock

Answer 5

Railway ballast has been made from many types of rock depending upon what's available in the area where the railway is located. Crushed limestone is fairly common, but I've seen everything from crushed granite to old cinders.
Here's a technical article that discusses ballast specifications:
http://www.civil.queensu.ca/people/faculty/raymond/Notes/845RailCourseNotes/6BAL-SPE.pdf
You can also find ads from various companies that supply ballast to railways by searching with "railway or railroad ballast".

There are two photos with identification of the rock type here. Scroll down to "Railroad Tracks".
http://saltthesandbox.org/rocks/find.htm

Another rock that's used is Basalt. Basalt is an extrusive igneous rock. Crushed basalt is used for railroad ballast, aggregate in highway construction, and is a major component of asphalt.
quote from: http://www.scienceviews.com/geology/minerals.html

Answer 6

Any kind of crushed rock can be used as a roadbed, but none of them float.

Answer 7

That is typically called Ballist , it is made with a rock crusher, normally 3 inch and smaller , also called railroad ballist.

Answer 8

pumise rock can float that I have found near a road. but your average rock on the road can not float