Santite, a new mineral phase from Larderello, Tuscany

1970 ◽  
Vol 27 (2) ◽  
pp. 159-165 ◽  
Author(s):  
Stefano Merlino ◽  
Franco Sartori
Keyword(s):  
2002 ◽  
Vol 66 (1) ◽  
pp. 173-179 ◽  
Author(s):  
A. C. Roberts ◽  
W. H. Paar ◽  
M. A. Cooper ◽  
D. Topa ◽  
A. J. Criddle ◽  
...  

AbstractVerbeekite, ideally PdSe2, monoclinic with space-group choicesC2/m,C2 orCm;a= 6.659(7),b= 4.124(5),c= 4.438(6) Å, ß = 92.76(3)°,V= 121.7(4) Å3;a:b:c= 1.6147:1:1.0761, Z = 2, is a new, very rare, primary mineral, intimately associated with secondary oosterboschite {(Pd,Cu)7Se5}, from the Musonoi Cu-Co-Mn-U mine, near Kolwezi, Shaba Province, Democratic Republic of Congo. Additional associated minerals are Cu- and Pd-bearing trogtalite {(Co,Cu,Pd)Se2}, Se-bearing digenite and Se-bearing covellite. The strongest five lines of the X-ray powder-diffraction pattern {din Å (I) (hkl)} are: 4.423(30)(001), 3.496 (30)(110), 2.718(100)(111), 1.955(50)(310 and 1.896(50)(l̄12). The mineral has also been identified, as a single anhedral 25 µm-sized grain, from Hope's Nose, Torquay, Devon, England where it is associated with native gold, chrisstanleyite Ag2Pd3Se4, oosterboschite(?), unnamed Pd2HgSe3and cerussite. At Musonoi, altered verbeekite grains do not exceed 200 µm in size and are anhedral, black, with a black streak and a metallic lustre. The mineral is opaque, brittle, has an uneven fracture, and lacks discernible cleavage. The VHN5ranges 490–610, mean 550 kp/mm2(2 indentations), roughly approximating a Mohs' hardness of 5Ý.Dcalc.= 7.211 g/cm3for the ideal formula. Electron-microprobe analyses (mean of 4 spot analyses) yielded Pd 39.6, Cu 0.5, Se 58.8, total 98.9 wt.%. The empirical formula is (Pd0.99Cu0.02)σ1.01Se1.99, based on Pd+Cu+Se = 3. In plane-polarized reflected light, the mineral is a nondescript grey and is neither pleochroic nor perceptibly bireflectant. Anisotropy is moderate with rotation tints in varying shades of brown. Reflectance spectra and colour values are tabulated. The name honours Dr Théodore Verbeek (1927–1991) who was the first geoscientist to study the Musonoi palladium mineralization in the Democratic Republic of Congo (1955–1967) and who co-discovered this new mineral phase.


Author(s):  
Aleksandr Borisovich Makeev ◽  
Boris Aleksandrovich Makeev ◽  
Sergey Evgen'evich Borisovskiy

Author(s):  
William F. Chambers ◽  
Arthur A. Chodos ◽  
Roland C. Hagan

TASK8 was designed as an electron microprobe control program with maximum flexibility and versatility, lending itself to a wide variety of applications. While using TASKS in the microprobe laboratory of the Los Alamos National Laboratory, we decided to incorporate the capability of using subroutines which perform specific end-member calculations for nearly any type of mineral phase that might be analyzed in the laboratory. This procedure minimizes the need for post-processing of the data to perform such calculations as element ratios or end-member or formula proportions. It also allows real time assessment of each data point.The use of unique “mineral codes” to specify the list of elements to be measured and the type of calculation to perform on the results was first used in the microprobe laboratory at the California Institute of Technology to optimize the analysis of mineral phases. This approach was used to create a series of subroutines in TASK8 which are called by a three letter code.


Author(s):  
Gejing Li ◽  
D. R. Peacor ◽  
D. S. Coombs ◽  
Y. Kawachi

Recent advances in transmission electron microscopy (TEM) and analytical electron microscopy (AEM) have led to many new insights into the structural and chemical characteristics of very finegrained, optically homogeneous mineral aggregates in sedimentary and very low-grade metamorphic rocks. Chemical compositions obtained by electron microprobe analysis (EMPA) on such materials have been shown by TEM/AEM to result from beam overlap on contaminant phases on a scale below resolution of EMPA, which in turn can lead to errors in interpretation and determination of formation conditions. Here we present an in-depth analysis of the relation between AEM and EMPA data, which leads also to the definition of new mineral phases, and demonstrate the resolution power of AEM relative to EMPA in investigations of very fine-grained mineral aggregates in sedimentary and very low-grade metamorphic rocks.Celadonite, having end-member composition KMgFe3+Si4O10(OH)2, and with minor substitution of Fe2+ for Mg and Al for Fe3+ on octahedral sites, is a fine-grained mica widespread in volcanic rocks and volcaniclastic sediments which have undergone low-temperature alteration in the oceanic crust and in burial metamorphic sequences.


1975 ◽  
Vol 14 (8) ◽  
pp. 368-375 ◽  
Author(s):  
E. A. Jobbins ◽  
Anne E. Tresham ◽  
B. R. Young
Keyword(s):  

1889 ◽  
Vol s3-37 (217) ◽  
pp. 67-70 ◽  
Author(s):  
H. L. Wells
Keyword(s):  

Priroda ◽  
2018 ◽  
pp. 12-20
Author(s):  
R. Rastsvetaeva ◽  
◽  
S. Aksenov ◽  
Keyword(s):  

Priroda ◽  
2018 ◽  
pp. 18-23
Author(s):  
S. Aksenov ◽  
◽  
R. Rastsvetaeva ◽  
Keyword(s):  

Author(s):  
S. Sukhanova ◽  
N. Pozdnyakova ◽  
F. Yaroslavtsev

The results of researches on the development of new mineral feed additives based on raw materials produced by Uralchem and the study of the eff ectiveness of their use in the rations of lactating cows have been presented in the article. The experiment has been carried out in the conditions of LLC “PF Barabinskoe” in the Dalmatovsky area in the Kurgan region where 3 groups of lactating cows of Black-and-White breed have been formed. Animals in the control group have been received the ration adopted in the farm, the 1st experimental group with the additive RusMA No. 1 at a dose of 150 g, the 2nd experimental group– with the additive RusMA No. 2 at the dose of 350 g. The use of experimental mineral additives in feeding lactating cows allowed us to increase their milk productivity and profi tability of production. At the same time, the best eff ectiveness was shown by the additive RusMA No. 2 at the dose of 350 g/head/day. The use of RusMA additives during the experiment period (105 days) allowed to increase the milk productivity of cows in the 1st experimental group by 6,03 % and in the 2nd experimental group by 8,24 %. Taking into account the fat content in milk, this diff erence was 6,31 and 8,53 %, respectively. The energy value of milk from cows of the experimental groups was higher compared to the control group by 2,45 and 1,76 %, respectively. According to the content of dry matter in milk, cows of the 2nd experimental group exceeded the control and 1st experimental group by 0,39 and 0,12 abs.%, respectively. The maximum milk fat content has been observed in the milk of cows of the 1st experimental group by 0,03 and 0,01 abs.% more than in the control and 2nd experimental groups, respectively. In terms of protein content, the cows of the 2nd experimental group signifi cantly exceeded the control group by 0,10 abs.% and the 1st experimental by 0,04 abs.%. The content of milk sugar in the 2nd experimental group was higher than in the control by 0,30 abs.% and compared to the 1st experimental by 0,11 %. Signifi cantly more calcium and phosphorus were contained in the milk of cows of the 2nd experimental group by 4,58 % (Р ≤ 0,001) and 2,86 % (Р ≤ 0,05), compared with the control group. The expenditures of feed in the EFU for the production of 1 kg of milk in animals of the 2nd experimental group was less by 5,13 % than in control cows and by 2,63 % compared to the 1st experimental group. The prime cost of 1 centner of milk was lower in the 2nd experimental group by 3,94 %, in the 1st experimental group by 2,65 % compared to the control group. The level of profi tability of milk production in the 2nd experimental group was higher by 9,0 and 1,0 abs.% in comparison with the control and 1st experimental groups, respectively.


Sign in / Sign up

Export Citation Format

Share Document