Rimstone/Travertine

Okay, so to make a long question sorta short, basically i love the mineral formation rimstone/gours. These are the kind you find in caves from the small cluster of them to the big pools. You can see the same design at Yellowstone National Park, Mammoth Hot Springs. I assume they are related? I understand in caves the crust forms around the water, but how is this so when in some places the water is moving over the formations pretty fast, in caves, and in mammoth hot springs.Also why is the rimstone found inside caves more "stronger" than that found at hot springs. Why does rimstone type formations not occur around a cold spring that is loaded with the needed minerals to build it. I have one time seen a type of spring called a chalybeate spring. It flowed from the side of a canyon wall, as it flowed down it went over and outcrop of rocks and made the water sorta "drip". under the large rock where the water was dripping was a beautiful stalactite, and stalagmite, with little gours all around the bottom of it. It looked like it was extremely fragile, but it was a scene that looked so much like a cave, but only above ground and very fragile.