pagmetite?

[wilfndgold]

Is this redish colored rock a Pagmetite?

 

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[Jim in Idaho]

Generally, A pegmatite is a rock that is coarse-grained, with often a large crystal structure. Usually, it occurs in dikes, or veins that intrude other rock. Look up a pic of kimberlite...it's a type of pegmatite.
On another subject...I raced in the Perris Grand Prix in 1971.
Jim

 

[Eu_citzen]

Is this really a satellite photo? Usually its not possible to say without at least a picture of a specimen.

Pegmatites can be any kind of coarse grained rock, but I've yet to hear kimberlite being called a pegmatite?

 

[Jim in Idaho]

I was wrong about that...just looked it up. Actually pegmatite isn't any coarse-grained rock. It has to be made up of large crystaline structure...usually of more than 1" diameter. But, all that said....the definition varies. Generally though, the rock has to be crystaline and of fairly course grain size...say more than 1/4" grains at the minimum. Most definitions say 1 cm minimum...larger than 3/8" crystals.
Jim

 

[Eu_citzen]

Hahah, reading all those definitions is fun! That's what I meant, the mineral grains have to be coarse/big, but both gabbro and granites can form pegmatites.
In school I learnt as a rule of thumb; if its larger then your thumbnail its a pegmatite.

 

[JLeonhardy]

I generally figure anything that looks like granite with a larger crystal structure is a pegmatite