After such a long pause I thought I would try an experiment. The old technique of choosing a topic from a text at random. The text chosen from a random book, in this case Titus Burckhardt’s, Alchemie (German edition). The random text from the book is about how the planetary symbols are composed of the circle, cross and the semicircle. (Interesting isn’t it? I just happened to open the chapter on the planets and the metals, where astrology and alchemy meet 🙂 )
From the alchemical point of view the Sun and Moon form two poles, male and female. Each works on or can be bound to indifferent matter (represented by the cross) in the center. So each of the five metals other than gold (☉) and silver (☽), each have a different ‘combination’ of solar and lunar influences on indifferent matter. Copper (♀) and Iron (♀ reversed – see below) both have solar influence. Tin (♃) and Lead (♄) have lunar influence. And not surprisingly Quicksilver (☿) has both lunar and solar influences.
Notice the old symbol for Mars – no arrow. Instead having the cross of matter above the solar circle makes more sense astrologically. In the order of the planets seen geocentrically
☽ ☿ ♀ ☉ ♂ ♃ ♄
Venus and Mars are closest to the Sun. Venus has a dominant solar circle. Venus/copper shows cosmic influence flowing into matter. Mars has a dominant cross of matter. Mars/iron shows material influence flowing into the cosmos.
Think about it. Iron is the metal that has made it possible for human beings to push matter into the cosmos. How? by surrounding/encasing ideas/vision with technology.
Titus Burkhardt refers to Basilius Valentinus when speaking about Venus or copper. Valentinus says that copper contains an abundance of unbound solar power much like a tree that has too much resin. Mars or iron is solar power that has become buried in the darkness of matter.
We can’t go into too much detail here. Consider this food for thought. You just might see Venus and Mars from an entirely new standpoint.
Altair Astrology 
thanks for posting, I have been seeing copper all over the place, (around homes, in stores, etc,) so very cool to have bounced across your post with Venus Mars and alchemy. Does also make me think of the work of Robert Zoller, he too spoke of astrology and alchemy.
Love your site, and love the impulse to explain the connection between the planets and alchemical/energetic principles. However, I have been taught something a little different than what you have posted, so am posting below.
Circle = Sun
Crescent = Moon
Cross = Matter (Earth/Man with outstretched arms…)
Planets
Mercury – A combination of all three symbols. Crescent receives intuitively from the heavens. Circle is the energy of spirit it brings, and the cross of matter is the manifestation of the reception and energy. This is why Mercury rules skills and craft.
Venus – Sun (energy/life force/divinity)+Cross(manifestation). Sensing the divine in the material is to experience love and beauty.
Mars – Matter + Sun. The direction of the manifestation is outward. We sense our own divinity/strength and express it physically.
Jupiter – Crescent + Cross. Receiving inspiration/understanding of how to manifest the these in combination (they are side-by-side in the symbol). Having perspective beyond the personal view of reality.
Saturn – Cross + Crescent. Matter compels one to tend to what we care for (Moon). Literally, sits on our feelings and sometimes this feels heavy, but it can stabilize our emotional world.
Uranus – Two Crescents + Cross + Sun – Ultra receptivity flow into inspired (Sun) manifestation (Cross). Invention. Brilliance. Sudden ideas/inspiration fueled by the energy of the Sun.
Neptune – Cross + Crescent – Here the crescent sits above the cross and provides inspiration/dreams that are intended for manifestation. Intuition takes precedence over matter.
Pluto – Circle + Crescent + Cross – The intuitive understanding and divine power/life force presiding over matter. This is why Pluto can be destructive, but it is the great cleanser. Clearing matter that is no longer working and replacing it with pure energy of the Sun and Moon.
Many blessings to you!
Kim
Hello Kim
Thank you for your contribution. Symbols, particularly older ones, have depth of meaning. There is always something new that can be brought to the surface.