a slaty sky
灰暗的天空
slaty rock
板岩
1.Slaty-backed Gull seems to be much the scarcest of the big gulls , I have seen only three, these following very cold weather.
大黑脊鸥似乎是台湾可见的大鸥中最稀少的一种，个人只看过三次，都是出现在非常冷的天气之后。
2.A metamorphic rock, intermediate between shale and slate, that does not possess true slaty cleavage.
厚层泥岩一种变质岩，在页岩与板岩之间，不具备真正的板块解理
3.The latter two rock types have a slaty to schistose structure, they are green in fresh state and show a silvery lustre on foliation planes.
后两种岩类有着从板状构造向片状构造的发展趋势，在清新状态下呈绿色，并在叶理面上显示一种银色光泽。