It occurs in cobalt bearing hydrothermal environments and was associated with veins of quartz and chalcedony in the type locality.
en.wikipedia.org In addition, it has been used to describe some forms of quartzite, bauxite, kaolinite, laterite, chalcedony, opal, and soda niter.
en.wikipedia.org The deposits lined and filled the cavity, first with a darker matrix material, then an inner core of agate or chalcedony.
en.wikipedia.org Despite its popularity over the decades, the area remains rich with chalcedony, citrine, quartz crystals, rhyolite and jasper.
en.wikipedia.org Among the more reactive mineral components of some aggregates are opal, chalcedony, flint and strained quartz.
en.wikipedia.org