His enthusiasm is enough to melt a heart of stone.

他的热诚足以软化铁石心肠。

《新英汉大辞典》

Today, I had a heart of stone.

可今天，我破例铁石心肠了一次。

youdao

I have a heart of stone.

我有一副铁石心肠。

youdao

In your pain and sadness, you may decide that the person you loved is hard-hearted, and in fact,has a heart of stone.

VOA: special.2010.07.18

Too long a sacrifice Can make a stone of the heart.

一种牺牲太长久了,能把心变为岩石。

耶鲁公开课 - 现代诗歌课程节选

If this happens, I might think that you have a heart of stone.

VOA: special.2010.07.11

" To the gardeners and janitors of the Vatican, "If we have a closed heart, we have a heart of stone.

CNN: Pope Francis' gestures strike fire in our hearts

It would take a heart of stone not to be inspired by the moment, so that even a tough businessman like Bezos was touch.

FORBES: Moon Rocket Engines Rise From the Ocean Depths

The church is at the heart of a lost-in-time village, full of rambling stone houses surrounded by wooded slopes where locals collect chestnuts in autumn.

BBC: A road trip through provincial France