Yes and No
What is sand?
Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of soil or soil type; i.e., a soil containing more than 85 percent sand-sized particles by mass.
The composition of sand varies, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal settings is silica (silicon dioxide, or SiO2), usually in the form of quartz.
Calcium carbonate is the second most common type of sand. One such example of this is aragonite, which has been created over the past 500 million years by various forms of life, such as coral and shellfish. It is the primary form of sand apparent in areas where reefs have dominated the ecosystem for millions of years, as in the Caribbean. Somewhat more rarely, sand may be composed of calcium sulfate, such as gypsum and selenite, as is found in places such as White Sands National Park and Salt Plains National Wildlife Refuge in the U.S. (Source)
So when other answers suggest that sand can come from creatures, it's a little misleading. It comes from the minerals of those creatures, like calcium carbonate (shells). Not just anything, and this is important. From that same source we read...
Sand is a non-renewable resource over human timescales, and sand suitable for making concrete is in high demand. Desert sand, although plentiful, is not suitable for concrete. Fifty billion tons of beach sand and fossil sand are used each year for construction.
In other words, all sand is not created equal. For example, whatever "sand" you can get from bone isn't suitable for creating integrated circuits, which specifically depends on silica.
Anything solid can be ground up into particles the size of sand. But does that make the result "sand?" The word is applied to a great many things and they're not all equal and they're not all interchangeable.
Which is a really long and fancy way of saying, "it works if the application you're thinking about is appropriate for it, and it doesn't work if it's not."
- Ground up silica is great for integrated circuits. Ground up bone is not.
- Ground up granite, gneiss and limestone is great for concrete. Ground up bone is not.
- Ground up silicon carbide is great for polishing rocks. Ground up bone is not.
- Ground up aluminum oxide is great for sandpaper. Ground up bone is not.
- Ground up calcium carbonate is great for antacid. Bone might be good for this, too... if prepared properly, because (for example) bone dust when breathed into the lungs can lead to Hepatitis B and C, Streptococci, and Human Immunodeficiency Virus (HIV).
So... yes and no.
On the whole and from a science perspective I'd vote no, bone sand would not behave like other sands. But it really depends on the application. In your case, where you're bringing magic into the mix, the answer is certainly yes. Thanks to the magic, bone sand would act like any other kind of sand due to narrative necessity. So if the question is, "would this be believable in the context of my world?" the answer is "oh, yeah!"