noun. A variety of silica that contains microcrystalline quartz.

noun. A siliceous rock of chalcedonic or opaline silica occurring in limestone.

noun. A cryptocrystalline variety of quartz, also called hornstone, petrosilex, or rock-flint.

noun. An impure, massive, flintlike quartz or hornstone, of a dull color.

noun. Massive, usually dull-colored and opaque, quartzite, hornstone, impure chalcedony, or other flint-like mineral.

noun. A flint-like tool made from chert.

noun. variety of silica containing microcrystalline quartz

"The Lake Superior iron formations now consist near the surface mainly of interbanded quartz (or chert) and hematite, called _jasper_ or _ferruginous chert_ or _taconite_."

chalcedony  flint  jasper  quartzite  silicate  

silica  silicon dioxide  silicon oxide  

taconite  

Bert  Curt  Evert  Insert  Kurt  

2950(dual  bloodstone  broad-bladed  clumsy-looking  cornelian