Talc Deposits Research Articles

Immature plate boundary zones studied with a submersible in the Gulf of California

The two spreading axes and a marginal transform fault in Guaymas Basin were examined during six dives to depths of 1,900 to 2,000 m in the submersible Sea Cliff . The plate boundary zones differ from those at mid-ocean ridges because of their youth: they are buried by thick sediment, partly derived from the adjacent continents whose rifted edges are still at the plate boundary along some transform faults. The accretionary margins have rift valleys bounded by normal fault scarps of diatomaceous mud; they are true grabens, not regenerating axial troughs like those at some mid-ocean ridges. The rifts are the main sites of turbidite deposition, igneous intrusion, and extensional faulting, processes that compete to level, buckle, and fracture the rift floors. Intrusion is by emplacement of sills and thicker bysmalith-like bodies, which episodically raise hills of folded and faulted semiconsolidated turbidites. Some of the fault scarps bounding the hills have very fresh, near-vertical faces, while others are cavernously weathered. A small hill within the Northern Trough has extensive young hydrothermal deposits of talc and sulfides on its crest and at a dissecting fault scarp. No extrusive volcanic rocks were found in the axial rift valleys nor at a marginal transform fault, where a belt of obliquely faulted sediments probably overlies the strike-slip axis. The transform-fault shear zone lies in a very asymmetric graben, with a sag at the edge of the basin floor and a fresh fault scarp truncating lithified sandstones on the continental side.

Asbestos in talc.

Talc deposits include asbestos minerals such as chrysotile and amphiboles that may be carried over into consumer products. Optical microscopy and x-ray diffraction analyses may not reveal their presence. Examples are given of electron microscopy procedures that permit detection and measurement.

Pulmonary Talcosis From Cosmetic Talcum Powder

The habitual use of large amounts of cosmetic talcum powder produced significant pulmonary talcosis in a 39-year-old black truck driver. Pulmonary disease was apparent on his chest roentgenogram, and was initially interpreted as miliary tuberculosis. The patient died from peritonitis following infarction of large segments of small intestine. Autopsy revealed extensive intraalveolar and interstitial deposits of talc in all lobes of both lungs. This case suggests that significant pulmonary disease may attend the overzealous use of cosmetic talcum powder.

Influence of hypothalamic deposits of antidipsic drugs on renal excretion

Antidipsic drugs, implanted bilaterally into the rat hypothalamus affected urine excretion. Urine volume was augmented and the osmolarity lowered, as compared to controls with hypothalamic talc deposits and deprived of water. The possibility that both effects, adipsia and polyuria, may result from inhibition of hypothalamic osmoreceptor function is discussed.

The lymphatics of the dog colon. A study of the lymph drainage patterns by indirect lymphography in the dog under normal and abnormal conditions.

A method of indirect lymphography in the dog colon is described. The technique was consistent in the opacification of draining lymph nodes which varied in number from 1 to 9 and averaged 4 per dog. The method confirmed the specific segmental distribution of lymphatics of the dog colon; in only one case did a nonsegmental node become opacified. Induced sterile inflammation by intramural deposition of talc in the colon wall resulted in a lymphographic picture characterized by: 1. increase in nodal size over control dogs; 2. increase in the average number of opacified nodes per dog; 3. increased incidence of nonsegmental node opacification; 4. decrease rather than increase in spread of retained intramural contrast medium. The findings reflected an increased lymph flow in the area of acute inflammation and suggested a wider than normal lymphatic distribution under such conditions. Acute mechanical obstruction of the dog colon at the rectosigmoid did not result in obvious increase in lymph flow. Node size and number opacified, as well as intramural spread of contrast medium, closely resembled controls. However, the distribution of lymphatic opacification was substantially influenced since all but one animal opacified a node outside the usual segmental drainage area. Resection of the lymphatic bed primarily responsible for drainage of the dog colon at the rectosigmoid resulted in edema of the involved portion of the bowel wall which disappeared partially or completely within 3 weeks. Indirect lymphography within a week of lymphatic resection demonstrated a marked intramural and paracolic spread of contrast material some 6 times greater than in control animals. When performed 3 weeks after resection, most dogs demonstrated opacified nodes although none were within the resected area. The intramural spread had decreased by 50%, reflecting the decrease in the edema and the establishment of collateral lymphatic circulation. Central lymphatic obstruction induced by intrathoracic, thoracic duct ligation resulted in marked lymphatic stasis and lymphedema. Decrease in nodal opacification and marked intramural spread were features noted in the early phase after obstruction. Within 2 weeks of duct ligation, lymphatic function increased and although the average number of opacified nodes resembled the control group, the presence of collaterals was increased. By 3 weeks, there was evidence of greater than normal lymph flow demonstrated by increased nodal opacification, both segmental and nonsegmental, and increased node size and filling. The intramural spread approached normal.

An experimental investigation of the system MgO-SiO 2 -H 2 O-CO 2

Equilibrium reactions of this system were experimentally investigated at pressures to 7000 bars and temperatures to 660 degrees C. Serpentine can coexist only with a CO 2 -poor fluid, and the lower stability limits of forsterite and talc are determined; talc is a metamorphic mineral at high pressures. The upper and lower stability limits of talc + magnesite are also determined and set limits on the temperature of formation of talc-bearing magnesite deposits and magnesite-bearing talc deposits. The conditions of origin for a number of types and specific localities of magnesite deposits are discussed in the light of these experimental studies.

Formation conditions of talc and soapstone deposits

Formation conditions of the talc and talc-carbonate rocks are discussed. A broad temperature range of talc formation is shown from a paragenetic study of minerals from the talc deposits. Also taken up is the relationship between composition of magnesium carbonates and oxidation potential and alkalinity of the medium. The possibility of tale formation at near-standard temperatures is demonstrated by thermodynamical calculations, as well as the equilibrium conditions for reactions talc + calcite ⇆⇄ dolomite + quartz and talc ⇆⇄ magnesite + quartz. The part of bimetasomatic infiltration processes is discussed with reference to talcite deposits. -- Author.

The Talc Deposits in Northern Kyusyu (I) : Distribution and Types of the Talc Deposits

The Talc Deposits in Northern Kyusyu (I) : Distribution and Types of the Talc Deposits

Talc deposits of North Carolina

Talc deposits of North Carolina

Talc deposits of North Carolina

Talc deposits of lenticular shape and irregular size occur in association with the Murphy marble over a length of some 40 miles in the extreme southwestern corner of North Carolina. The marble is one of a series of sedimentary formations of Cambrian age and passes by gradations into the underlying and overlying formations. Along either side of the marble belt the rocks have been intruded by quartz-diorite dikes that are younger than the structures in the enclosing formations. Field and microscopic evidence indicate that the talc lenses were formed by hot solutions of magmatic origin. The quartz-diorite dikes seem to have been the source of the solutions that produced the mineralization.

Serpentinization, origin of certain asbestos, talc, and soapstone deposits; discussion

Serpentinization, origin of certain asbestos, talc, and soapstone deposits; discussion

The origin of the talc and soapstone deposits of Virginia

The origin of the talc and soapstone deposits of Virginia

Origin of the Vermont talc deposits, with a discussion on the formation of talc in general

Origin of the Vermont talc deposits, with a discussion on the formation of talc in general