Riebeckite forms in two very different habits. The darker-colored forms which are individually crystallized are generally of igneous origin, such as volcanic rock and pegmatites. The finely fibrous variety, known as Crocidolite, usually originates from altered metamorphic rocks. The Crocidolite variety is a type of asbestos, and is sometimes also referred to as "blue asbestos". It is considered to be the most hazardous form of asbestos, and should never be brought near the mouth. If its fibers or particles enter the lungs, they can cause asbestosis. Asbestosis is a lung disease caused by inhalation of asbestos particles, which causes several cancers, particularly lung cancer and mesothelioma. Symptoms of asbestosis do not arise until about 20 years after the inhalation. Due to the hazards, washing hands after handling specimens is highly recommended. Many mineral collectors avoid collecting asbestos minerals out of safety concerns.

Riebeckite forms a series with Magnesio-riebeckite, which is the magnesium-dominated end member which has magnesium replacing part of the iron in its structure. Riebeckite crystals are frequently included within larger crystals of Quartz, and will sometimes turn the Quartz a blue color if the inclusions are very fine. Riebeckite was named after the German explorer and mineralogist Emil Riebeck (1853–1885).

Tiger's Eye, a well-known inexpensive gemstone, is a pseudomorph of compact Quartz after finely the fibrous Crocidolite variety of Riebeckite. It is formed when the Quartz takes over and dissolves the Crocodolite, leaving the Quartz compact yet composed of solid fibrous - and chatoyant forms. When polished, it's silky luster creates a beautiful chatoyant effect of moving layers of brown and yellow lines and waves.