Magmatic iron-titanium ores

Haemoilmenite. Allard Lake, Quebec, Canada

Large crystals of an ilmenite host (brown) contain irregular exsolution discs of haematite (white) plus very fine-grained haematite exsolution bodies (bottom left). Multiple twinning is present (north-south orientation, lower reflectance, right), some of which can be confused with parallel scratches (northwest-southeast orientation, left) in plane polarized light. Black areas are polishing pits and fractures, many of the polishing pits are concentrated along twinning of the ilmenite.

Polished block, plane polarized light, x 80, air

Haemoilmenite and rutile. Allard Lake, Quebec, Canada

Four crystals of haemoilmenite (brown), showing reflection pleochroism from dark to light brown, carry abundance crystallographically oriented haematite (white) exsolution bodies. The largest haemoilmenite (right) contains an area (bottom right) of rutile (lilac-grey) surrounded by haematite (white, higher reflectance). Dark grey area (bottom right) is silicate and black areas are fractures.

Polished block, plane polarized light. x80, air

Haemoilmenite, ilmenohaematite and rutile. Allard Lake, Quebec, Canada

Haemoilmenite comprises an ilmenite host (pink-brown) with exsolution bodies of haematite parallel to (0001) of the host ilmenite. The larger haematite bodies themselves carry further ilmenite exsolution bodies (centre) and rutile laths (lilac-grey, oriented cast-west, centre right). Later incipient alteration along fractures (black) has resulted in poor polishing.

Polished block, plane polarized light, x 160. oil

Haemoilmenite, ilmenohaematite and rutile. Allard Lake, Quebec, Canada

Haemoilmenite crystals comprise an ilmenite host (pink browns) which shows faint reflection pleochroism and haematite exsolution bodies which contain fine-grained exsolved ilmenite (ilmenohaematite) (bottom left). Many of the ilmenohaematite bodies carry rutile laths (lilac-grey, centre left) which are oriented perpendicularly to the fine-grained ilmenite exsolution. The dark grey area is silicate and black areas are polishing pits.

Polished block, plane polarized light, x 160, oil

Haemoilmenite, ilmenohaematite and rutile, Allard Lake, Quebec, Canada

The ilmenite (pink-brown) host carries fine discoid haematite exsolution bodies parallel to (0001) and coarser ilmenohaematite (white) which in turn has fine-grained ilmenite exsolution (centre). Coarse-grained rutile (lilac-grey, centre) is common within ilmenohaematite. The concentration of fine haematite exsolution bodies within the ilmenite decreases towards the coarser grained ilmenohaematite and so shows a seriate distribution. Black areas are polishing pits.

Polished block. plane polarized light, x 160, oil

Haemoilmenite, ilmenohaematite and rutile. Allard Lake. Quebec, Canada

The ilmenite host (pink-brown) has fine- and coarse-grained haematite (white, bottom left) exsolution bodies oriented along the (0001) direction of the ilmenite. The coarse-grained ilmenohaematite has fine ilmenite exsolution within it. Rutile (lilac-grey, left) is oriented perpendicularly to the crystallographic orientation of the main exsolution bodies.

Polished block, plane polarized light. x 160, oil