It takes the form of a web or matrix of spindly threads, which are usually about .4mm in thickness and between 1 and 4 cm in length. The nodes of the web connect between 4 and 12 threads, averaging on 8. The structure and shape of the web is irregular, and contains mostly empty space, giving it overall a very low density.   The surface is white, slightly translucent, and emits a faint light such that it is barely visible in darkness.

It has physical resistance and strength greater than that of steel, but higher conductivity and a lower melting point, similar to mundane calcium. It is also very brittle, but when broken, melted, or otherwise reshaped, it gradually returns to its web form.   Magnacalcum is the only known alchemical material to readily make more of itself: if left in contact with mundane calcium, it will convert it into more of itself, growing slowly according to a specific pattern: nodes that are in contact with calcium will split, with a new thread forming between the new and old nodes, while pre-existing threads are split between them.

Incorporates itself seamlessly with bone, such that its presence is very difficult to discern except by applying chemical or biological agents that remove the bone's carbon compounds and leave the magnacalcum compounds behind.

Is frequently found in the bones of all sorts of creatures; those in contact with alchemical raw magic almost invariably contain traces of it, as do any who live more than 40 or so years. All Dragons have at least some in their bones, with ancients having thick webs throughout their skeletons that greatly increase their durability. It is also found within most Dwarves.

Is probably the most stable of alchemical materials: it only oxidizes in air at over 15 psi. Corrosion appears in random locations, usually near the surface of the matrix, and appears as rough, matte, and dark grey splotches. If these completely cover the material, it will return to mundane calcium. Corrosion can be prevented entirely by keeping the material in water.

Although its strength is advantageous, its inability to retain a convenient shape makes it unusable for most purposes to which other metals are applied. Instead, the most common use is as a stabilizer in bricks or concrete, giving buildings much higher strength.

Being based in a lesser metal, it is difficult to manufacture, and a reliable method has yet to be invented. However, its ability to self-replicate makes such necessities moot: those wishing to make more magnacalcum do so by acquiring a small piece and placing it in a container of mundane calcium, preferably in powdered form. The process is time-consuming, but reliable.