Finally figured one out that works for me, not too salty or abrasive.
10ml (2tsp) Diatomaceous Earth (food grade). ~ rich in silica, gentle polisher.
5ml (1tsp) Bentonite Clay ~ gentle polisher, mineral rich, detoxifying.
10ml (2tsp) Cal/Mag powder 2:1 ratio (this is sold as a drink mix). ~ re-mineralizing.
10ml (2tsp) Baking Soda ~ gentle polisher, bacteria eliminator.
10ml (2tsp) Organic Orange/Lemon Peel Powder. ~ natural whitening agent.
5ml (1tsp) Fine Sea Salt ~ gentle polisher, natural anti-bacterial.
50ml (3Tbsp+1tsp) GMO-free Xylitol (I powdered this in a spice mill first) ~ anti-bacterial, decay prevention, plaque reducer, sweetner.
*optional - 10 drops liquid trace minerals (sprinkle in and mix, if you wish you can run everything in a spice mill to make sure the liquid combines evenly with the powder). ~ re-mineralizing.
Combine all ingredients well and store in an air tight container. Use just a pinch on a wet or dry toothbrush. (Any powdered substance should not be inhaled, take care with that.)
If you would like to flavour your tooth powder you may add a maximum of 20 drops essential oil of your preference. I used a combination of fennel, wintergreen, and cinnamon which is quite nice.
-This makes 100ml of dry powder but I've found that bathroom humidity can cause it to clump up so keep just a bit on hand and the rest in an airtight container in a cool, dark spot.
-I've read some reports that the DE and/or clay can cause tooth discolouration with prolonged use. I recommend use of this as a polisher a few times/week alternating with regular toothpaste, plain salt, plain baking power, or simply water on it's own.