Joe's Rock Shop – Orderville, Utah

Septarian Nodules

“The hills west of Orderville are the source of one of Utah’s best known mineralogical exports, the septarian nodule. The word “septarian” means a roughly spherical concretion with a compact crust and an internal mass broken with angular cracks that widen toward the center and are filled, or partly filled, with a foreign mineral or crystals. ”
-Gem Trails of Utah, James R. Mitchell


Septarian concretions (from Wikipedia)

a septarian nodule

Septarian concretions or septarian nodules, are concretions containing angular cavities or cracks, which are called “septaria“. The word comes from the Latin word septum; “partition”, and refers to the cracks/separations in this kind of rock [1]. There is an incorrect explanation that it comes from the Latin word for “seven”, septem[2], referring to the number of cracks that commonly occur. Cracks are highly variable in shape and volume, as well as the degree of shrinkage they indicate. Although it has commonly been assumed that concretions grew incrementally from the inside outwards, the fact that radially oriented cracks taper towards the margins of septarian concretions is taken as evidence that in these cases the periphery was stiffer while the inside was softer, presumably due to a gradient in the amount of cement precipitated.

The process that created the septaria, which characterize septarian concretions, remains a mystery. A number of mechanisms, i.e.the dehydration of clay-rich, gel-rich, or organic-rich cores; shrinkage of the concretion’s center; expansion of gases produced by the decay of organic matter; brittle fracturing or shrinkage of the concretion interior by either earthquakes or compaction; and others, have been proposed for the formation of septaria (Pratt 2001). At this time, it is uncertain, which, if any, of these and other proposed mechanisms is responsible for the formation of septaria in septarian concretions (McBride et al. 2003). Septaria usually contain crystals precipitated from circulating solutions, usually of calcite. Siderite or pyrite coatings are also occasionally observed on the wall of the cavities present in the septaria, giving rise respectively to a panoply of bright reddish and golden colors. Some septaria may also contain small calcite stalagtites and well-shaped millimetric pyrite single crystals.

Joe's Rock Shop has been in southern Utah since the early 1950s and is owned by Ken & LaTeresa Caruso. Ken's father, Joe Caruso, was the shop's founder, namesake and well known area philanthropist. Joe's Rock Shop is located in Orderville, Utah and specializes in cutting and polishing of Septarian Nodules and Petrified Wood.