Zach likes this substrate better because it costs more than sand. Mick, Wichita Falls Reptile Rescue, TX, February 6, 2008. One point I would like to make in regards to the information that you do have up, is that ground walnut shell should not be used as a substrate for these lizards. It is an impaction hazard. I worry that a novice with a newly bought Horned Lizard might see this and go buy ground walnut or something worse.
Radon is a chemical element with symbol Rn and atomic number 86. It is a radioactive, colorless, odorless, tasteless noble gas, occurring naturally as a decay product of radium. Its most stable isotope, 222Rn, has a half-life of 3.8 days.Radon is one of the densest substances that remains a gas under normal conditions.adon is produced by the radioactive decay of radium-226, which is found in uranium ores, phosphate rock, shales, igneous and metamorphic rocks such as granite, gneiss, and schist, and to a lesser degree, in common rocks such as limestone.
Radon is everywhere but some parts of the country are more likely to have high levels in buildings than others. We have worked with the British Geological Survey to produce a data set and maps of the radon prone areas.