It is not a common Antique chip but more common in the color WHITE than any other color.
There are several things to consider with an engraved Antique chip like this. Dale valued the chip "H" in 1998 and there are very few ENGRAVED Antique chips that are valued H. An H valued Engraved Antique chip is not just "scarce" but it is actually RARE IMHO. Engraved chips of this type were usually offered in RED, WHITE, & BLUE and packaged for sale in a box of 100 that included 25 RED, 25 BLUE, & 50 WHITE. Many Antique Engraved & Embossed chips were also available in YELLOW in lots of 16 to be added to a set for HIGH denominations. With that said your White chip would be the most common of the PE-GM "Mermaid" chips. I have found the chip in White and Red but I do not recall ever seeing it in Blue. I doubt that this chip was ever offered in Yellow. Engraved Clay composition poker chips were first made post 1880 and the PE-GM Mermaid chip is not illustrated in the catalog section of Dale's book so we can only speculate that it might have been in the late 1800s. I would value your chip in the $50 range as it is in great condition but probably not quite that much until the stimulus package kicks in. Very nice find Ruben!