Triangular system

N & gt2.7

Crystallization characteristics: the crystal is a polygon with a bottom axial surface and a rhombic surface. It is often thick plate, thin plate or even leaf-shaped. Thin plates are often dendritic skeleton and hexagonal cross-section, sometimes elongated rhombic, irregular granular and dense block. The twins at the joint surface (10 1 1) are well developed. The ordinary cleavage of {101} can bend along the cleavage of {000 1}.

The characteristics in the film are opaque, and the edge is slightly transparent when it is extremely thin, dark brown to purple brown, and it is brown-black under reflected light. Gloss is dimmer than magnetite and hematite. Because it often turns into white titanium ore, white is often seen under reflected light. The common acicular ilmenite inclusions in pyroxene (especially orthopyroxene), amphibole and plagioclase are arranged regularly.

The change usually turns into white titanium along the edge of ilmenite crystal or the whole crystal, and the white titanium is white cotton wool-like and opaque under the reflected light.

Identification features The ilmenite sheet is opaque, similar to magnetite and hematite, but the shape characteristics of rhombohedral crystals and dendritic skeleton crystals of ilmenite and their frequent transformation to white titanium can be identified.

Ore occurrences and other ilmenites are mainly produced in mafic rocks, especially diabase and trachyte. The gas products related to alkaline rocks are also rich in ilmenite. Ilmenite also exists in some metamorphic rocks, such as gneiss, mica schist and amphibole. Ilmenite often occurs in pyroxene, amphibole and plagioclase in the form of needle-like and flaky inclusions. It exists in clastic rocks in the form of clastic minerals.