Correct

花岗岩脑袋

/ huā gǎng yán nǎo dài /
Strokes
https://i.cchatty2.com/filters:format(webp)/fit-in/684x0/img/202102/花岗岩脑袋-Chinese-idioms-Cchatty-262a1d1a-0dd4-485c-8632-eb3b6b48d94d-1612778060.jpg

Collocation

1
花岗岩脑袋不开化
2
花岗岩脑袋不开窍
3
……的脑袋是花岗岩
4
有着花岗岩脑袋的人
5
……是花岗岩脑袋

Definition

花岗岩脑袋

Literally means:

granite brain

Actually means:

ossified thinking

Granite is type of very firm rock. This phrase figuratively means one is very stubborn or sticks to old ideas and is unlikely to accept new ideas or new.

花岗岩,一种很坚硬的石头。比喻人的思想顽固,或者人十分守旧,不能接受新思想,新事物。具有贬义色彩。

Example

Used as predicate, object or attributive, and it can have other words in between and can be used in inversion. (作谓语、宾语、定语,中间可插入别的的词语,也可倒装)
1
Gǎi
改革
kāifàng
开放
lái
以来
  
,
shǐ
即使
jiā
大家
de
xiǎng
思想
dōu
kāifàng
开放
le
  
,
huāgāngyán
花岗岩
nǎodài
脑袋
de
rén
háishi
还是
huì
yǒu
de
  

Since the reform and opening up, even if everyone's mind is open, granite head people will still have.

2
píng
批评
pínfán
频繁
tiàocáo
跳槽
  
,
jiù
gōng
攻击
shì
huāgāngyán
花岗岩
nǎodài
脑袋
  
,
néng
shíjìn
与时俱进
  
Méi
xiǎngdào
想到
de
wāizhēn
歪理可真
shǎo
不少
ā
  

I criticize you for jumping ship frequently, and you attack me as a granite head that can't keep pace with the times. I didn't expect you to be so crooked.

3
kāiwánxiào
开玩笑
shuō
  
:
shi
zǒng
shuō
lǎogōng
老公
de
nǎodài
脑袋
shì
huāgāngyán
花岗岩
zuò
de
  
,
xiàng
一向
shǒujiù
守旧
  
,
zěnme
怎么
huì
tóng
同意
zhí
辞职
kāi
离开
gōng
公司
ne
  
?

I joked: "You don't always say your husband's head is made of granite, always old-fashioned, then how could he agree to you resign from the company?"