A rational intergrowth of two or more single crystals of the same mineral in a mathematically describable manner, so that some lattices are parallel whereas others are in reversed position. The symmetry of the two parts may be reflected about a common plane, axis, or center.

shape two crystals joined together Cerussite, Staurolite

A condition within quartz stone where the optic and/or the electric axis suddenly reverse its natural order of polarity.

arrangement between institutions in different geographical locations in which students complete up to two years of study in a college in their home countries, followed by guaranteed admission to the partner university for completion of a degree program; the degree is granted by the latter institution

Causing an embryo to split in half, producing two identical embryos.

A process by which an morula, blastocyst or embryo divides in half to produce twins with identical genetic makeup. This normally happens at some time up to the 14th day after fertilization, before the "primitive streak" appears. Twinning does rarely happen later that 14 days and produce conjoined twins; these are popularly called "Siamese twins'

Development of monozygotic twins, that is, when a very early embryo separates into two pieces, each of which continues development, so that two embryos actually come from one zygote.