When the sulfur reaches the surface in the springs it is oxidized to form sulfuric acid. The pH's of the water is 4.5 or less generally. In the acidic water the siliceous sinter formed is spiny and not the rounded masses found around hot spring pools in other Yellowstone basins. The geyserite deposits are not as extensive here as in other basins and lacks large cone build-ups. Also the pools and springs here have coloration different than other Yellowstone basins.
Some pools are milky blue from dissolved silica in the water.
This is common particularly on the southern edge of Porcelain Basin in pools like Sunday Geyser. The yellows seen in some pools can be native sulfur. Acid tolerant cyanidium algae gives some pools and runoff streams a lime green color while in cooler runoff streams particularly in The Porcelain Basin. Orangish cyanobacteria may be found in some springs. Him Write Her WyoJones's Geyser Page.