Concretion Necklace Septarian Nodule
Insouciant Studios "Concretion" Necklace featuring a lovely arrangement of natural lavender blue angelite stone beads and a cut and polished septarian nodule concretion with sterling construction & lobster clasp. This is an interesting piece, feminine yet bold.
Total Length 18 1/4 inches (45 cm)
Center Focal: 1.5 inches wide, 1.25 inches long (4 x 3.2 cm)
About the Materials:
Angelite, otherwise known as Anhydrite in a mineralogical context, is an evaporite mineral often found in association with gypsum, sulphur, halite, calcite, and dolomite. It is a member of the Anhydrous Sulfate Group, with chemical formula CaSO4 (Calcium Sulfate). Anhydrite and gypsum are the only rock forming sulfate minerals. Anhydrite has a hardness of 3-2.5 on the Mohs scale (so fairly soft) , and a pearly or vitreous luster. In pure form, this mineral is colorless, with color coming (as usual) from minute quantities of other elements within the crystal lattice. [Mineralogy, Perkins]
Mineral Concretions are a fascinating class of sedimentary structure, formed in unconsolidated or poorly consolidated sediments. These structures typically form through the actions of groundwater movement and mineral precipitation about a nucleus of some sort, often organic in composition, such as a leaf, tooth, bone, shell, or fossil. Concretions are usually spherical or disc shaped, and can be composed of a variety of minerals, including calcite, dolomite, pyrite, barite, or microcrystaline silica (agate).
Septarian Nodules are a type of concretion notable for visible internal cracks, later filled with other mineral precipitates, commonly calcite. The origin of these cracks is not well understood, but hypotheses about their formation abound. This particular septarian nodule shows calcite, pyrite, and some silicious (agate) and oxide minerals.