PNG as an icon / button with PNG

Ionic Framework ionic-v3
1

Hi,
I need to have tabs with my images, so I tried to save ion-icon with my image but it failed

ion-icon {
   /* &[class*="before-"] {
        // Instead of using the font-based icons
        // We're applying SVG masks
        mask-size: contain;
        mask-position: 50% 50%;
        mask-repeat: no-repeat;
        background: currentColor;
        width: 1em;
        height: 1em;
    }
   
 &[class*="before-icon"] {
    mask-image: url(../assets/icon/Stage11.sgv);
}

How can I do it with a different way?
Thank you!