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The best-formed small (less than 10-mm) spinel crystals have been found in the salmon-pink calcite, whereas the best larger spinel crystals and the best corundum pseudomorphs appear to occur in gray calcite toward the center of the vein-dikes. Epitaxy of magnesiohögbomite on an octahedral face of spinel crystal overgrown by another spinel crystal from the DeWitts Corners occurrence. Due to the composite nature of the spinel crystals (see further on), magnesiohögbomite crystals can be found on faces of spinel crystals that have been overgrown by other crystals when forming larger composite spinel crystals (fig. 13). This locality, little known among mineral collectors, is a source of unusual spinel specimens, aesthetic pseudomorphs of corundum after spinel, and superb specimens of two polytypes of magnesiohögbomite. [Extracted from the article]

Takahashi et al. ([5]) successfully produced lab-grown scepter quartz using the microchannel epitaxy concept by artificially masking the prism faces of a quartz crystal with silver and leaving the apex unmasked. First, crystals tend to grow roughly perpendicular to the walls of the vein because any other orientation would put these crystals at a disadvantage in the competition with other crystals for space. All specimens pictured from the Lyndhurst area, Ontario, Canada Quartz is a common and deceptively simple mineral that keeps giving us riddles. Quartz crystals were found in hydrothermal quartz veins located in light beige to light gray quartzite (meta-sandstone) interlayered with gneiss. [Extracted from the article]

The new högbomite-group mineral magnesiohögbomite-6N12S, ideally Mg5Al11TiO23(OH), was found in calcite "vein-dikes" at the DeWitts Corners occurrence, lots 10 and 11, concession 1, Bathurst Township, Ontario, Canada. It forms tabular and short-prismatic crystals up to 5 mm in size. The major forms are pinacoid {0001} and hexagonal pyramid {11 ${\bar 2}$ 1}, sometimes modified by hexagonal prism {11 ${\bar 2}$ 0}. The associated minerals are magnesiohögbomite-2N3S, spinel, corundum, diopside, magnesio-hastingsite, pargasite, clinochlore and calcite. Magnesiohögbomite-6N12S is dark brown to black with brown streak and vitreous lustre. It has no cleavage and its fracture is uneven. The Mohs hardness is 6½. Dcalc is 3.87 g/cm3. The infrared spectrum is reported. The composition (wt.%) is MgO 13.09, ZnO 0.46, FeO 11.91, Fe2O3 6.84, Al2O3 62.70, TiO2 4.44, H2O 0.99, total 100.43. The empirical formula calculated on the basis of 17 cations, excluding H+, is (Mg2.95Fe2+1.51Al0.49Zn0.05)Σ5(Al10.71Fe3+0.78Ti0.51)Σ12O23(OH). The simplified formula is (Mg,Fe)5(Al,Fe,Ti)12O23(OH). The mineral is trigonal, R ${\bar 3}$ m, a = 5.7194(2), c = 83.069(5) Å, V = 2353.3(2) Å3 and Z = 6. The strongest reflections of the powder X-ray diffraction pattern [d,Å(I)(hkl)] are: 2.921(26)(0.1.23), 2.863(49)(110), 2.687(29)(0.1.26), 2.547(31)(0.1. $\overline{28}$) and 2.434(100)(1.1.18). The crystal structure was solved and refined from single-crystal X-ray diffraction data to R1 = 0.022. It is composed of alternating spinel (S) and nolanite (N) modules in the sequence 3 × (NSSNSS). The sequence of cubic 'c' and hexagonal 'h' closed-packed oxygen layers is 3 × (cccccchcccch). It is the first polysome in the högbomite supergroup with such a sequence. [ABSTRACT FROM AUTHOR]