Examples of index fossils. Index fossils (also known as guide fossils, indicator fossils or zone fossils) are fossils used to define and identify geologic periods (or faunal stages).
Methyl cellulose. Methyl cellulose (or methylcellulose) is a chemical compound derived from cellulose. It is a hydrophilic white powder in pure form and dissolves in cold (but not in hot) water, forming a clear viscous solution or gel.
The rule: All carbonates are insoluble EXCEPT: ammonium carbonate and Gr1 alkali metal carbonates. In accordance with this, lithium carbonate is soluble in water. But its solubility is not as high as, for example Na2CO3 solubility of Li2CO3 = 15.4 g/L (0 Â°C),13.2 g/L (20 Â°C), 7.2 g/L (100 Â°C).