The specialty chemical maker Aurorium, formerly known as Vertellus, has informed Indiana authorities that it will close its pyridine chemical plant in Indianapolis. The facility employs about 159 people. Pyridine is used to make vitamin B3 and herbicides such as paraquat. The firm closed part of the plant in 2016, while it was in bankruptcy. It is the only pyridine facility in the US and, according to the Vertellus website, the world’s largest pyridine producer.