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The mantle is very fragile,

The mantle is very fragile, and breaks easily. If the wick was even slightly bumped before it was burned, or bumped as it was put into the box by the manufacturer, it'll flame up broken like that. It's either a storage method change you need, or maybe contact the seller and return it for a good one. I once had an entire box of Aladdin mantles get smashed in transit, didn't know it until I went to light them and they immediately had holes.