Aplite is an intrusive rock essentially composed of quartz and alkali feldspar (usually in the form of either orthoclase or microperthite). Quartz is a hexagonal crystallised form of silica or silicon dioxide, and alkali feldspar is a solid solution between the K-feldspar (a compound made up of one atom each of potassium and aluminium, three atoms of silicon and eight atoms of oxygen) and albite (a compound made up of one atom each of sodium and aluminium, three atoms of silicon and eight atoms of oxygen) endmembers. It usually has very fine grains. It may be white, grey or flesh-coloured.
Aplite is a very tiny rock and its constituents are not visible to the naked eye. A very powerful magnifying glass is required to see the fine constituents of the aplite rock. Aplite dykes and threads frequently traverse through granitic bosses and occasionally also occur in syenites, diorites, quartz-diabases and gabbros. Petrologists have made an interesting observation that genetically, aplites invariably have a special affinity to the rocks they intersect. For example, the aplites found in granite areas are the last part of the magma to crystallise.
Aplite is a very tiny rock and its constituents are not visible to the naked eye. A very powerful magnifying glass is required to see the fine constituents of the aplite rock. Aplite dykes and threads frequently traverse through granitic bosses and occasionally also occur in syenites, diorites, quartz-diabases and gabbros. Petrologists have made an interesting observation that genetically, aplites invariably have a special affinity to the rocks they intersect. For example, the aplites found in granite areas are the last part of the magma to crystallise.