• Secondary magnetite

Secondary magnetite is present in all studied clinopyroxenites in amounts from 0.5 to 5–10%. In clinopyroxene, it consists of grains less than 0.05 mm in size of isometric or angular shape, which are localized in the cleavage cracks of this mineral, occasionally in the intergrowth with interstitial actinolite (Figure 5a). In olivine, thin veinlets or chains of small secondary magnetite grains fill the central part of cracks filled with serpentine (Figure 8a,b). At the contact of large olivine and pyroxene grains, tiny parts of secondary magnetite "are gathered" in larger porous aggregates in serpentine or form symplectic intergrowths with serpentine or tremolite (Figures 5c,d and 8a). Secondary magnetite in clinopyroxenites II and III overgrows interstitial sulfide segregations or, in clinopyroxene III, its crystals are enclosed in pyrite or chalcopyrite (Figure 2b–d). In contrast to primary magnetite with elevated content of Cr, Ti, and V (Table 4), the contents of trace elements in secondary magnetite are lower and, typically, are below the detection limit or error of analysis (Table 8).


3 101012-37 90.14 0.63 0.65 *0.02* 0.1 0.12 0.54 92.20 4 211015\_3\_9 94.18 b.d. b.d. b.d. b.d. b.d. b.d. 94.18 5 211015\_5\_1 89.89 b.d. b.d. b.d. b.d. 0.37 b.d. 90.26

**Table 8.** Chemical composition of secondary magnetite (in wt.%).

Note. Samples of clinopyroxenites I (No 1), II (No 3,4) and III (No 5). Analyses: 1,5—in symplectic intergrowths with amphibole; 2—microveinlets in serpentine; 3—inclusion in bornite-chalcopyrite lattice-like aggregate; 4—overgrown on large pyrite segregations.
