Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Natrophilite is a mineral with the chemical formula NaMnPO4. In a pure form it has a yellow coloration. Its crystals are orthorhombic to dipyramidal. It is transparent to translucent. It is not radioactive. Natrophilite is rated 4.5 to 5 on the Mohs Scale. A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound. The chemical formula identifies each constituent element by its chemical symbol and indicates the number of atoms of each element found in each discrete molecule of that compound.