The silicate anion in the mineral kinoite is a chain of three ${\mathrm{SiO}}_4$ tetrahedra units that share corners with adjacent tetrahedra. The mineral also contains ${\mathrm{Ca}}^{2+}$ ions, ${\mathrm{Cu}}^{2+}$ ions and water molecules in a $1 : 1 : 1$ ratio. The mineral is represented as.

Three tetrahedral units that combined together by sharing oxygen atoms at the corner. Therefore, the structure of the silicate and its formula is:

The negative charge is neutralized by the same number of positive charge. Charge of one Ca is +2 and one Cu is +2. Ratio of ${\mathrm{Ca}}^{2+}$ and ${\mathrm{Cu}}^{2+}$ is 1:1, therefore there must be two ${\mathrm{Ca}}^{2+}$ and two ${\mathrm{Cu}}^{2+}$ions, so that total cationic charge is +8 and neutralizes the -8 charge of the silicate. Number of water molecules has the same ratio that of ${\mathrm{Ca}}^{2+}$ and ${\mathrm{Cu}}^{2+}$ ions, hence the mineral has two water molecules. 

Formula of mineral comes out to be ${\mathrm{Ca}}_2{\mathrm{Cu}}_2{\mathrm{Si}}_3{\mathrm{O}}_{10}·2{\mathrm{H}}_2\mathrm{O}$ in which the ratio of water, ${\mathrm{Ca}}^{2+}$ and ${\mathrm{Cu}}^{2+}$ is 1:1:1 and is neutral because the positive charge is balanced by the negative charge.