Preheat the oven to 400 F. Line a large baking sheet with parchment paper and set aside.
In a large bowl, whisk together the flour, salt, baking powder, baking soda, sugar, and lemon zest.
Cut the butter into ¼-inch cube.s Use your hands to rub the butter into the dry ingredients until the mixture resembles coarse crumbs.
In a small bowl whisk together the egg, ½ cup buttermilk, Greek yogurt, and vanilla extract. Add the wet ingredients to the flour mixture and mix until just moistened.
Add the blackberries and gently fold them into the dough until incorporated.
Place the dough onto a lightly floured surface. Use your hands to shape the dough into an 8-inch circle. Cut the dough into 8 equal-sized wedges and transfer them to the prepared baking sheet.
Brush the scones with the remaining 2 tablespoons of buttermilk.
Bake in the preheated oven for 18-20 minutes, until the tops are a light golden brown.
While the scones are cooling, make the glaze by mixing together the lemon juice and powdered sugar.