Alkaline igneous rocks of Magnet Cove, Arkansas: Mineralogy and geochemistry of syenites

Zr- AND Ba-RICH MINERALS FROM THE PONTE NOVA ALKALINE MAFIC-ULTRAMAFIC MASSIF, SOUTHEASTERN BRAZIL: INDICATION OF AN ENRICHED MANTLE SOURCE

“…In the southern satellite area, Ba-rich feldspar is easily found as an interstitial phase, oikocrysts enclosing submillimetric chadacrysts of plagioclase, and even as a mantle surrounding other feldspar grains (Fig. 7A), as in other magmatic occurrences (Flohr & Ross 1990, Zhang et al 1993a. In general, Ba-rich alkali feldspar crystals of the southern satellite area tend to be normally zoned, with decreasing levels of Ba toward the rim.…”

Mineralogical and chemical composition of samples from the Christy vanadium-titanium deposit, Hot Spring County, Arkansas

“…The relative contribution of these events to the formation of the vanadium ore is difficult to evaluate because of the intensity of the alteration. Flohr and Ross (1990) point out that Ti, Nb and V are compatible elements in the Magnet Cove intrusive complex and accumulated in primary minerals. Autometasomatic reactions may have redistributed a portion of these elements into residual fluids some of which migrated into the country rock, including the Christy deposit.…”

“…The concentrations of other elements overlap with the ranges for the igneous rocks in the intrusive complex and none were considered sufficiently diagnostic to identify the compositions of the precursor igneous rock. The large titanium contents of the argillized dikes is attributed to titanium oxides that most likely formed by alteration of Ti-rich minerals that are common in many of the intrusive rocks of Magnet Cove (Erickson and Blade, 1963;Flohr and Ross, 1990).…”

“…Autometasomatic reactions may have redistributed a portion of these elements into residual fluids some of which migrated into the country rock, including the Christy deposit. Expulsion of the multiple residual fluids generated by the different phases of the intrusive complex (Flohr and Ross, 1990;Flohr, 1991) are recorded by the zoned quartz and fluid inclusions (Willis, 1992). Less permeable blocks of the Paleozoic rocks were altered thermally to form hornfels and recrystallized novaculite.…”

Zirconium and hafnium

“…V3). Depending on future price fluctuations, economic concentrations of zirconium and hafnium ore minerals might also be recovered from tailings of primary igneous deposits, particularly in alkaline igneous provinces, such as in central Arkansas (Flohr and Ross, 1990). These two examples highlight the potential for recoverable resources from tailings in a wide variety of settings where zircon is not or was not the primary commodity of interest in the past but may be present at economic concentrations and is also relatively easy to extract.…”