STONE MASON FRUIT JAR UNION STONEWARE CO. RED WING MINN.

Item is a STONEWARE MASION FRUIT JAR UNION STONEWARE CO. RED WING, MINN. This is stamped on the side of the jar in blue lettering. The color of the jar is oatmeal with blue specks in it. It is a quart stoneware jar. The screw top has a slight chip. the bottom of the base has a small hairline crack toward the edge and on the flat bottom base has a dot, brown and hard like glass. Inside the jar in the bottom looks like a patch of the same material,towards the edge. Can you tell me if this came from the manufacture? had it filled with water ,never leaked.

The lid cover is not original. It is a ATLAS JAR 14-2 GENUINE BOYD'S CAP FOR MASON

Could you tell me anything about it and what it could worth?

                                                                          thank you