Crocoite

Beautiful saffron-colored crocoites are brittle and rarely faceted or worn as jewelry. If subjected to streak testing, crocoite crystals, like these on display at the Smithsonian National Museum of Natural History, will leave an orange streak. However, they'll likely break. Photo by Tim Evanson. Licensed under CC By-SA 2.0.

Article: Destructive Gemstone Tests: Streak Testing

Credit: Tim Evanson