This is what Encyclopaedia Britannica says about Mithras mythology:
(WRITTEN BY: Reinhold Merkelbach
LAST UPDATED: 8-18-2016 See Article History)
https://www.britannica.com/topic/Mithraism'
MYTHOLOGY AND THEOLOGY
The creation of the world is the central episode of Mithraic mythology. According to the myths, the sun god sent his messenger, the raven, to Mithra and ordered him to sacrifice the bull. Mithra executed the order reluctantly; in many reliefs he is seen turning aside his face in sorrow. But at the very moment of the death of the bull, a great miracle happened. The white bull was metamorphosed into the moon; the cloak of Mithra was transformed into the vault of the sky, with the shining planets and fixed stars; from the tail of the bull and from his blood sprang the first ears of grain and the grape; and from the genitals of the animal ran the holy seed which was received by a mixing bowl. Every creature on earth was shaped with an admixture of the holy seed. One Mithraic hymn begins: “Thou hast redeemed us too by shedding the eternal blood.” The plants and the trees were created. Day and night began to alternate, the moon started her monthly cycle, the seasons took up their round dance through the year, and thus time was created. But, awakened by the sudden light, the creatures of the dark emerged from earth. A serpent licked the bull’s blood. A scorpion tried to suck the holy seed from the genitals. On the reliefs a lion often is also seen. With the bull’s death and the creation of the world, the struggle between good and evil began: thus is the condition of human life. The raven symbolizes air, the lion fire, the serpent earth, and the mixing bowl water. So the four elements (air, fire, earth, and water) came into being, and from them all things were created. After the sacrifice, Mithra and the sun god banqueted together, ate meat and bread, and drank wine. Then Mithra mounted the chariot of the sun god and drove with him across the ocean, through the air to the end of the world.
The myth was interpreted by the Roman Mithraists in terms of Platonic philosophy. The sacrifice took place in a cave, an image of the world, as in the simile of the cave in Plato’s Republic. Mithra himself was equated with the demiurge, or creator, of the Timaeus: he was called “demiurge and father of all things,” like the Platonic demiurge. The four elements, the mixing bowl, the creation of time, and the attack of the wicked animals upon the newborn creature are well-known features of the Timaeus. The Mithraic doctrine of the soul is intimately linked with the myth of creation and with Platonic philosophy. As in the Timaeus, the human soul came down from heaven. It crossed the seven spheres of the planets, taking on their vices (e.g., those of Mars and of Venus), and was finally caught within the body. The task of human life is to liberate one’s divine part (the soul) from the shackles of the body and to reascend through the seven spheres to the eternal, unchanging realm of the fixed stars. This ascent to the sky was prefigured by Mithra himself, when he left the earth in the chariot of the sun god.'_______
This is an explanation of Demiurge:
https://en.wikipedia.org/wiki/Demiurge_______
a) So, is it possible that the figure on the left represents the Demiurge, the horse and rider Mithras, and the figure on the right perhaps represents the bull? The sun emblem incorporated because of the importance of the sun in the Mithras mythology/belief?
Therefore the whole depiction on my vase might reference/be depicting Mithras, rather than a task of Herakles?
The drawings on my vase, definitely appear to have been taken from Mr Thomas Kirk's engravings which date to c.1804 and were taken from Sir Williams Hamilton's drawings.
But they are taken from two separate drawings as I showed previous, with the figure on the left being taken from one, and the two figures on the right along with the sun depiction being taken from another drawing.
Perhaps the designer of the picture on my vase designed the picture to represent Mithras hence using two different drawings.
b) Or does it as previously discussed, represent one of Herakles tasks, showing Herakles, Hippolyta and Iobates ?
But that myth does not explain the reason or relevance of the sun depiction in either the plate or my vase.
The book with Mr Kirk's plates in it, has only some meandering thoughts as to why the sun might be on the plate and indeed one of the descriptive paragraphs of the plate starts 'This plate is
supposed to represent Hyppolyta engaged with Hercules ...'
My underlining, and note it uses the phrase '...supposed to represent ...' rather than '...represents...'.
https://archive.org/stream/outlinesfromfig00hami/outlinesfromfig00hami#page/25/mode/1upsee pages 25 and 26
This the description of the plate of the Horse and rider and the man with weapon seen on my vase:
'Plate XL
Hipployta, queen of the Amazons, wore the girdle of Mars, as an emblem of the country she reigned over: Admeta , the daughter of Euristheus, became envious of this honour, and wished to possess the girdle. In consequence of this desire, Hercules received orders to procure it. This is the ninth of the labours, which this god undertook at the request of his brother. He immediately went to the banks of the river Thermodoon, which the Amazons inhabited. Juno, always at variance with, and hating Hercules, had recourse to her usual cunning, and caused the girdle, which he would have obtained as a gift, to become the cause of a most obstinate conflict between Hercules and the warlike Amazons.
This Plate is supposed to represent Hippolyta engaged with Hercules, in which combat, according to Apollodorus, the Amazonian queen lost her life. The meaning of the ray of sun over Hercules and the horse is uncertain: the Chaldeans called the planet Mars, Hercules: and there is also a constellation under the same name. It is probably one of these three things, that it is intended to denote.'[/b]
In my opinion it is not at all certain from the authors description in that book, that that plate definitely represents the myth of Hercules and Hippolyta's belt.
In my opinion it is possible that both the Plate 40 from the book, and the depiction on my vase (with an additional third figure to the two on the Plate from the book), could represent Mithras instead.