Becquerelite forms beautiful lustrous yellow transparent crystals, generally too small to be appreciated except under a microscope. Becquerelite forms in oxidation zones of sedimentary uranium deposits, and is occasionally found in pegmatites. It is often found in association with uraninite, as it is one of the weathering products of that mineral.
Becquerelite is part of the Comperignacite - Billietite series, which vary primarily by a substitution of calcium with potassium (in comperignacite) or with barium (in billietite).
Remember, this is a radioactive mineral and should be stored away from other minerals that are affected by radioactivity and human exposure should definitely be limited. However, note that radioactivity is relative: uranium is not very radioactive compared to most unstable isotopes. This is easy to understand, as the uranium has been slowly and steadily decaying since the Earth was formed approximately 4.5 billion years ago. Since the half-life of the most common uranium isotope, U-238, is 4.47 billion years, only half of the Earth's U-238 remains. The isotope used in nuclear reactors and bombs, U-235, has a half-life of 704 million years, so only 1.2% of the Earth's original supply remains. A very highly radioactive substance decays much more rapidly, and there is none left on Earth except through the continuing decay of elements such as uranium. For example, radon has a half-life of 3.8 days. A gram of pure radon therefore decays 450 billion times faster than a gram of U-238 - it is 450 billion times as radioactive.