Xray Ultimate is a popular, easy-to-install Minecraft resource pack that makes common blocks transparent to highlight valuable ores for efficient mining. It features outlined ores for better visibility in dark caves and can be toggled via the in-game resource pack menu. Download it at CurseForge CurseForge Xray Ultimate - Minecraft Resource Packs - CurseForge
For the latest files, check the official CurseForge page: Xray Ultimate - Files - Minecraft Resource Packs