Diamonds are forever, unless you’re on Saturn or Jupiter. Loads of the super-hard precious stones may be floating among the gas giants’ fluid layers and melted into liquid further into their depths, say a pair of planetary scientists.
The research, being presented at the Division for Planetary Sciences conference this week [Oct, 2013] in Denver, sprang from very humble beginnings — soot in Saturn’s atmosphere, said Kevin Baines, a planetary scientist at the University of Wisconsin-Madison and one of the work’s coauthors.
New studies of ancient concrete could teach us to do as the Romans did
July 3, 2017
Around A.D. 79, Roman author Pliny the Elder wrote in his Naturalis Historia that concrete structures in harbors, exposed to the constant assault of the saltwater waves, become “a single stone mass, impregnable to the waves and every day stronger.”
He wasn’t exaggerating. While modern marine concrete structures crumble within decades, 2,000-year-old Roman piers and breakwaters endure to this day, and are stronger now than when they were first constructed. University of Utah geologist Marie Jackson studies the minerals and microscale structures of Roman concrete as she would a volcanic rock. She and her colleagues have found that seawater filtering through the concrete leads to the growth of interlocking minerals that lend the concrete added cohesion. The results are published today in American Mineralogist.
Romans made concrete by mixing volcanic ash with lime and seawater to make a mortar, and then incorporating into that mortar chunks of volcanic rock, the “aggregate” in the concrete. The combination of ash, water, and quicklime produces what is called a pozzolanic reaction, named after the city of Pozzuoli in the Bay of Naples. The Romans may have gotten the idea for this mixture from naturally cemented volcanic ash deposits called tuff that are common in the area, as Pliny described.