Trying to match old mortar

I have a 55-year-old cut squared block stone house. The stone is in need of tuck-pointing in some areas.
First off is it called tuck-pointing when it is not brick but stone? The other thing is how do I go about to try to mix matching mortar? It looks like a lot of aggregate (sand) was used in the motor.
Is there a good site about how to mix mortar to match old mixes? Or is there a service where I can send a piece of the mortar and get a formula for its mix. Because of its age am I actually seeing it aged in color too and a pigment may be needed also? Is there mortar that is only lime and no cement? Help!
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Talk to local masons , cement yards, a city paid architect-free, For my Indiana Limestone it took White portland and tint, plus it should not be harder than the stone itself. Its a real tough job to match it , but ive done it 20 times. Research with your city, and go for it done right.
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Make a soft mortar with 2 -3parts lime to 1 part portland and 8 parts sand. portland comes in white or gray. If you can dissolve out a sample of the existing mortar with acid you can get a better look at the sand originally used.
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What would I be using to try to devolve the sand out?
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