[…] Matter is running down and the universe itself will one day become extinct. An everlasting and immitigable nothingness, in the void of black and absolute−

In (b), a paperwall model for a crystal.

It also occurs in Mongolia and Soviet Siberia. It is produced mainly in Nei Mongol, Gansu, and Xinjiang.

I know of no other genera with such intramarginal formation of true gemmae.