These are some of the samples of gypsum which are on display at the Smithsonian Museum of Natural History. The sample at left is gypsum formed with quartz and is from Irai, Rio Grande do Sul, Brazil.
The above sample of gypsum is similar to the gypsum curls I have seen growing out of cave walls. It is displayed at a size close to its real size. The large sample at right is probably 15 cm high.
These thin gypsum needles are shown about actual size.