So much space is given to machine made marble names - why not look to hand made stone agates for a breath of fresh air?
Definition -- Chalcedony a hard stone deposit, usually formed into a
football size solid nodule or hollow geode by a long process of water
evaporation and a layered deposition of dissolved mineral impurities.
Common types are agate, carnelian (aka cornelian), moss agate and onyx
Onward --In my view agates that found their way into kids marble bags
or game boards were never larger than 3/4. (Cant grip with index finger
for shooting!) Some vintage eye candy faceted agates greater than 1.5
exist but most are contemporary. All German agate marbles were facetted
and probably more for eye appeal - dyed with sugar, sulfuric acid, arsenic
along with other nasty chemicals - then often exposed to UV light to
produced intense bands of black, yellow, blue, white and a rare green.
When geode - nodule supplies ran out in Germany - eastern Brazil had
plenty of exactly the same agate geode - nodules! -- (thanks to Continental
Drift) --
Beware of marbles made of lapis lazuli, tigers eye, moss agate, lace
agate, bloodstone or any other exotic mineral, they were probably
purchased at a gem and mineral show and slipped into the secondary
market or at least not made for a marble bag.
Spoiler Alert! Some years back -there were skillful grinders taking
orders to custom apply facets or ground pontils!
Some of the mineral information was taken from Wikipedia. Thats my story
and Im sticking to it!
Big Indian