Picrit

Picrit (Pikrit). A Ger industrial expl, prepd from surplus stocks left after WW1. It consisted of PA in which up to 10% could be substituted by any aromatic nitrocompd which would not make the expl more dangerous to handle than straight PA... 

Picrite. Brit name for Nitroguanidine (NGu),. also known as Guany] Nitramine. See in Vol 6, G154-R ff... 

Current propellent explosives may be divided into three classes single base, double base and composite however double base propellants which contain picrite are often considered a separate class and called triple base. 

Ordnance propellants are required to give the minimum of muzzle flash, smoke and barrel erosion. All these objectives are assisted by adding to the propellant a proportion of nitroguanidine (picrite), made by treating guanidine nitrate with sulphuric acid and brought to very fine particle size by recrystallisation and disintegration. 

Triple base propellant. A propellant containing nitroglycerine, nitrocellulose and Picrite. 

The Baffin Bay picrites (Francis, 1985) show a very good covariation of FeO, MgO, and Ni. Defined from the twelve XRF data listed in Table 1.12, the variables x = ln(FeO/MgO) and y = ln(Ni/MgO) have been fitted by the parabolic equation... 

Figure 1.11 Ni/MgO vs FeO/MgO relationship for the Bay of Island basalts and picrites (Table 1.12 data from Francis, 1985). The curve is a least-square parabolic fit through the data. Since D = MgoFe° remains constant, the DMg0Nl partition coefficient increases with increasing FeO/MgO [equation (1.5.10)].

DMgoNi increases from 1.5 for a picrite with FeO/MgO=0.5, to 3.2 for a differentiated basalt with FeO/MgO = 3, values that are consistent with the range found by Arndt (1977) and Hart and Davis (1978). o... 

Cumulate control lines vs liquid lines of descent. In a study of the 1931-1986 basaltic eruptions from the Reunion Island (Indian Ocean), Albarede and Tamagnan (1988) found the Ni and Cr concentrations (in ppm) listed in Table 3.1 and shown in Figure 3.2. Samples with Ni>100ppm were found to contain large amounts of cumulus olivine. The last five samples of Table 3.1 are picrites. The smooth trend observed for all the rocks is suggestive of a complementary fractionation-accumulation relationship out of a single magma batch. Therefore, it is asked whether the trend observed for Ni and Cr in basalts with less than 100 ppm Ni may be ascribed to the removal of the olivine found in the cumulates. 

Figure 3.2 Plot in log-log scales of the Ni and Cr concentrations (ppm) in post-1930 basalts (open symbols) and picrites (solid symbols) from the Piton de la Fournaise volcano, Reunion Island, Indian Ocean (Albarede and Tamagnan, 1988).

Francis, D. (1985). The Baffin Bay lavas and the value of picrites as analogues of primary magmas. Contrib. Mineral. Petrol., 89, 144-54. 

Morgan Z., Liang Y., and Hess P.C. (2006) An experimental study of anorthosite dissolution in lunar picritic magmas implications for crustal assimilation processes. Geochim. Cosmochim. Acta 70, 3477-3491. 

Nitroguanidine (NGu, Picrite), Pentaerythri-tol Tetranitrate (PETN), RDX (Cyclonite, Cyclotrimethylenetrinitramine, Hexogen), Tetranitrocarbazole (TeNCbz, TeNC), Tetryl (Trinitrophenylmethylnitramine) and TNT (Trinitrotoluene Trotyl)... 

AlFa to between 565—840° (Ref 1). Found as a mineral in Germany. Has been used in some propellants and pyrotechnic compns For example, Brit Cordite N contd NC (13,1% N) 19-0, NG 18.5, NGu(Picrite) 54.7, EtCentr 7.5 K3A1F6(called Cryolite in Ref 2) 0.3% with added chalk 0.15%. A similar proplnt known as Type HPM contd ... 

The following proplnt compns were listed in a British Report Type N NC(13-1% N) 19-0, NG 18.7, NGu (Picrite) 55.0 EtCentr(Carbamite) 7.3% with Na3AlFe 0.3% added... 

Nitroguanidine or Picrite, dry or wetted with less than 20 per cent water, by mass 0282... 

Nitroguanidine, wetted or Picrite, wetted with not less than 20 % water, by mass 1336... 

Gun and rocket propellants are based on nitrocellulose (NC-SB), NC with NG as second principal ingredient (DB) and nitroguanidine (picrite) in addition to NC and NG ( ) propellants. Propellant formulations also contain stabilizer, plasticizer, coolant and ballistic modifier, in addition to their principal ingredients. 

Several cool proplnts were developed after WWII in Great Britain. They contd NGu (Picrite) in addn to NG (or DEGDN) and NC. Their compns are given in ARE Rept of 1954 (Ref 37). Erosive action of these proplnts was tested in I7-pounder gun barrels made of Ni-Cr-Mo steel and results reported in Ref 37... 

It must be noted that the two non-picrite proplnts of FT = 1950°K were different in that one (F487/68) contd 14.3% DEGDN, while the other (F428/180) contd 15.4% NG. The results of comparative trials, as was... 

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