UNICO INCORPORATED (AZ) (fka UNCO)

[GOLDENBOLLOX]

To NYBOB on Unico

All three Unico properties have something in common.

Bromide
Deer Trail
Silver Bell

The common denominator is that they are all hydrothermal, skarn type in nature

Volcanic and granite related hydrothermal circulation

Hydrothermal circulation is not limited to ocean ridge environments. The source water for geysers and hot springs is heated groundwater convecting below and lateral to the hot water vent. Hydrothermal circulating convection cells exist any place an anomalous source of heat, such as an intruding magma (granite) or volcanic vent, comes into contact with the groundwater system.

Deep crust

Hydrothermal also refers to the transport and circulation of water within the deep crust, generally from areas of hot rocks to areas of cooler rocks. The causes for this convection can be:

* Intrusion of magma into the crust
* Radioactive heat generated by cooled masses of granite
* Heat from the mantle
* Hydraulic head from mountain ranges, for example, the Great Artesian Basin
* Dewatering of metamorphic rocks which liberates water
* Dewatering of deeply buried sediments

Hydrothermal circulation, particularly in the deep crust, is a primary cause of mineral deposit fomation and a cornerstone of most theories on ore genesis.

Skarns

Skarns are a class of calc-silicate rocks and are intimately associated with granite intrusions, usually of sedimentary-metamorphic origin (S-type). Skarns are rarely seen with other types of granites, because of the fluid chemistry and crystallization behaviour of M-type (mantle origin) and I-type (igneous-metamorphic origin) granites. S-type granites are more prone to generating late-stage fluid rich in silica, incompatible elements and halides because they are generally more potassic, oxidised and hydrous.

Exoskarns are formed when fluids left over from the crystallisation of the granite are ejected from the mass at the waning stages of emplacement. When these fluids come into contact with reactive rocks, usually carbonates such as limestone or dolostone, the fluids react with them, producing alteration (metasomatism).

Because these fluids carry dissolved silica, iron, metals, halides and sulfur, the resulting rock is usually a highly complex combination of calcium, magnesium and carbonate rich minerals.

Uncommon types of skarns are formed in contact with sulfidic or carbonaceous rocks such as black shales, graphite shales, banded iron formations and, occasionally, salt or evaporites. Here, fluids react less via chemical exchange of ions, but because of the redox-oxidation potential of the wall rocks.

Endoskarns are rarer, generally because the fluids created by a granite are usually formed in equilibrium with the minerals of the granite. Endoskarns seem to form in granites which lose earlier, more dilute hydrous fluids, thereby creating a less dilute last spurt of exsolved fluids. Boiling of the exsolved fluid is also considered important, as this creates a highly saline, incompatible-element-rich fluid phase and a highly volatile gas phase.

Skarns are often hosts for copper, lead, zinc, iron, gold, molybdenum, tin, and tungsten ore deposits.