Alkaline earth element with symbol Ra and atomic number 88 <http://periodic.lanl.gov/88.shtml>
This category is also used for Ra.
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Global rare earth element occurrence database

Geologic occurrence of rare earths, including mineralogy, type of deposit or occurrence, host rocks and alteration, and any quantitative data related to size and grade from publicly available data. 3,934 locations are described, including some locations for which precise geographic coordinates are not available.