Replacement texture
Hydrothermal setting – minerals
Porosity – the mineral being replaced can develop a porosity during the alteration process;
Rim replacement – the neo-mineral growth along (or replaces) the rim of the older one, sometimes penetrating along crystallographic planes (which makes it resemble an exsolution).
Zonal replacement (atoll texture) – occurs in zoned minerals, because inner zones of a given composition can be easier to replace than the rim of the mineral.
Core replacement – idem as zonal replacement, with the core area being the easiest to repalce.
Relict texture, pseudomorph – mineral entirely replaced by another one, with the general habitus of the former mineral being preserved. The neo-phase can form fine-grained aggregates (e.g., sericitization of feldspar).
Bird eye texture – a type of replacement along fracture that produces circular features, e.g., pyrite + marcasite replacing pyrrhotite (due to weathering of pyrrhotite).
Sub-graphic intergrowth – only one of the two minerals involved in the graphic intergrowth is replaced.
Irregular replacement – this can also mimic a graphic intergrowth (mineral type should tell them apart).
Lattice intergrowth - replacement along preferred crystallographic planes.
Chalcopyrite disease – partial replacement of sphalerite by chalcopyrite.
Chessboard texture – K-felspar partially replaced by Na-feldspar.
Caries – generally displayed by a host mineral that lacks cleavage. The replacing phase forms embayment that are convex toward the host (i.e., the new mineral seems to bit into the old one). Note that the curvature can be concave toward the host for other mineral association, the orientation of the curvature is not diagnostic.
Hydrothermal setting – rocks
Selective replacement – at the scale of the rock, some minerals are replaced while others remain untouched.
Ongonite – a rock that consists entirely of hydrothermal minerals (e.g., quartz, alkali-feldspar) but that has retained the magmatic texture of the precursor.
Quartz flooding – silicification (deposition of fine-grained quartz) that gives a vitreous look to the rock. The rock generally retains its pre-silicification texture (and mineralogy, for the most part).
Layering induced by replacement - can occur due to:
Partial replacement of the rocks, with fluids circulating along parallel pre-existing planar structures, e.g., fractures, foliation planes.
Rock replaced by distinct minerals as the composition of the fluid evolves (and early deposited hydrothermal minerals can be replaced as well), which induces zoning.